Plasma processing assembly using pulsed-voltage and radio-frequency power

ABSTRACT

Embodiments of the disclosure provided herein include an apparatus and method for the plasma processing of a substrate in a processing chamber. More specifically, embodiments of this disclosure describe a biasing scheme that is configured to provide a pulsed-voltage (PV) waveform delivered from one or more pulsed-voltage (PV) generators to the one or more electrodes within the processing chamber. The plasma process(es) disclosed herein can be used to control the shape of an ion energy distribution function (IEDF) and the interaction of the plasma with a surface of a substrate during plasma processing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional patentapplication Ser. No. 17/959,074, filed Oct. 3, 2022, which is acontinuation of U.S. Non-Provisional patent application Ser. No.17/315,256, filed May 7, 2021, which claims the benefit of U.S.Provisional Patent Application Ser. No. 63/059,533, filed Jul. 31, 2020,and U.S. Provisional Patent Application Ser. No. 63/150,529, filed Feb.17, 2021, each of which are herein incorporated by reference in itsentirety.

BACKGROUND Field

Embodiments described herein generally relate to semiconductor devicemanufacturing hardware and processes, and more specifically to anapparatus and methods of controlling the delivery of power to a plasmaformed in plasma processing chamber used in semiconductor manufacturing.

Description of the Related Art

Reliably producing high aspect ratio features is one of the keytechnology challenges for the next generation of very large scaleintegration (VLSI) and ultra large scale integration (ULSI) ofsemiconductor devices. One method of forming high aspect ratio featuresuses a plasma assisted etching process, such as a reactive ion etch(RIE) plasma process, to form high aspect ratio openings in a materiallayer, such as a dielectric layer, of a substrate. In a typical RIEplasma process, a plasma is formed in an RIE processing chamber and ionsfrom the plasma are accelerated towards a surface of a substrate to formopenings in a material layer disposed beneath a mask layer formed on thesurface of the substrate.

A typical Reactive Ion Etch (RIE) plasma processing chamber includes aradio frequency (RF) bias generator, which supplies an RF voltage to a“power electrode” (e.g., a biasing electrode), such as a metal platepositioned adjacent to an “electrostatic chuck” (ESC) assembly, morecommonly referred to as the “cathode”. The power electrode can becapacitively coupled to the plasma of a processing system through athick layer of dielectric material (e.g., ceramic material), which is apart of the ESC assembly. In a capacitively coupled gas discharge, theplasma is created by using a radio frequency (RF) generator that iscoupled to an RF electrode through an RF matching network (“RF match”)that tunes the apparent load to 50Ω to minimize the reflected power andmaximize the power delivery efficiency. The application of RF voltage tothe power electrode causes an electron-repelling plasma sheath (alsoreferred to as the “cathode sheath”) to form over a processing surfaceof a substrate that is positioned on a substrate supporting surface ofthe ESC assembly during processing. The non-linear, diode-like nature ofthe plasma sheath results in rectification of the applied RF field, suchthat a direct-current (DC) voltage drop, or “self-bias”, appears betweenthe substrate and the plasma, making the substrate potential negativewith respect to the plasma potential. This voltage drop determines theaverage energy of the plasma ions accelerated towards the substrate, andthus etch anisotropy. More specifically, ion directionality, the featureprofile, and etch selectivity to the mask and the stop-layer arecontrolled by the Ion Energy Distribution Function (IEDF). In plasmaswith RF bias, the IEDF typically has two non-discrete peaks, one at alow energy and one at a high energy, and an ion population that has arange of energies that extend between the two peaks. The presence of theion population in-between the two peaks of the IEDF is reflective of thefact that the voltage drop between the substrate and the plasmaoscillates at the RF bias frequency. When a lower frequency RF biasgenerator is used to achieve higher self-bias voltages, the differencein energy between these two peaks can be significant; and because theetch profile due to the ions at low energy peak is more isotropic, thiscould potentially lead to bowing of the etched feature walls. Comparedto the high-energy ions, the low-energy ions are less effective atreaching the corners at the bottom of the etched feature (e.g., due tothe charging effect), but cause less sputtering of the mask material.This is important in high aspect ratio etch applications, such ashard-mask opening or dielectric mold etch. As feature sizes continue todiminish and the aspect ratio increases, while feature profile controlrequirements become more stringent, it becomes more desirable to have awell-controlled IEDF at the substrate surface during processing.

Other conventional plasma processes and processing chamber designs havealso found that delivering multiple different RF frequencies to one ormore of the electrodes in a plasma processing chamber can be used tocontrol various plasma properties, such as plasma density, ion energy,and/or plasma chemistry. However, it has been found that the delivery ofmultiple conventional sinusoidal waveforms from two or more RF sources,which are each configured to provide different RF frequencies, is unableto adequately or desirably control the sheath properties and can lead toundesirable arcing problems. Moreover, due to direct or capacitivecoupling between the RF sources during processing, each RF source mayinduce an RF current that is provided to the output of the otherconnected RF source(s) (e.g., often referred to as the “cross-talk”),resulting in the power being diverted away from the intended load(plasma), as well as a possibly causing damage to each of the RFsources.

Accordingly, there is a need in the art for novel, robust and reliableplasma processing and biasing methods that enable maintaining a nearlyconstant sheath voltage, and thus create a desirable and repeatable IEDFat the surface of the substrate to enable a precise control over theshape of IEDF and, in some cases, the etch profile of the featuresformed in the surface of the substrate.

SUMMARY

Embodiments of the disclosure provided herein include an apparatus andmethod for the plasma processing of a substrate in a processing chamber.More specifically, embodiments of this disclosure describe a biasingscheme that is configured to provide a pulsed-voltage (PV) waveformdelivered from one or more pulsed-voltage (PV) generators to the one ormore electrodes within the processing chamber. The plasma process(es)disclosed herein can be used to control the shape of an ion energydistribution function (IEDF) and the interaction of the plasma with asurface of a substrate during plasma processing.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlyexemplary embodiments and are therefore not to be considered limiting ofits scope, and may admit to other equally effective embodiments.

FIG. 1A is a schematic cross-sectional view of a processing chamberconfigured to practice methods described herein, according to oneembodiment.

FIG. 1B is a schematic cross-sectional view of a processing chamberconfigured to practice methods described herein, according to oneembodiment.

FIG. 1C is a schematic cross-sectional view of a packaging assembly thatis coupled to a processing chamber, according to one embodiment.

FIG. 1D is a schematic cross-sectional view of an alternate version of apackaging assembly that is coupled to a processing chamber, according toone embodiment.

FIG. 2 is a simplified schematic diagram of a biasing scheme that can beused with the process chamber illustrated in FIG. 1A or 1B, according toone embodiment.

FIG. 3A is a functionally equivalent circuit diagram of a negative pulsebiasing scheme that can be performed in the process chamber illustratedin FIG. 1A or 1B, according to one embodiment.

FIG. 3B is a functionally equivalent circuit diagram of a positive pulsebiasing scheme that can be performed in the process chamber illustratedin FIG. 1A or 1B, according to one embodiment.

FIG. 3C is a functionally equivalent circuit diagram of a coulombicelectrostatic chuck (ESC) that can be used in the process chamberillustrated in FIG. 1A or 1B, according to one embodiment.

FIG. 3D is a functionally equivalent circuit diagram of a Johnsen-RahbekESC that can be used in the process chamber illustrated in FIG. 1A or1B, according to one embodiment.

FIG. 4A illustrates an example of negative pulsed voltage (PV) waveformsestablished at the biasing electrode and substrate, according to oneembodiment.

FIG. 4B illustrates an example of a series of pulse voltage (PV)waveform bursts, according to one or more embodiments.

FIG. 4C illustrates an example of a series of pulse voltage (PV)waveform bursts, according to one or more embodiments.

FIG. 4D illustrates an example of an ion energy distribution function(IEDF) formed by a series of pulse voltage (PV) waveform bursts,according to one or more embodiments.

FIG. 5A illustrates an example of a negative pulsed voltage (PV)waveform established at the biasing electrode, according to oneembodiment.

FIG. 5B illustrates an example of a shaped pulsed voltage (PV) waveformestablished at the biasing electrode, according to one embodiment.

FIG. 5C illustrates an example of a positive pulsed voltage (PV)waveform established at the biasing electrode, according to oneembodiment.

FIG. 5D illustrates a comparison of a negative pulsed voltage (PV)waveform and a positive pulsed voltage (PV) waveform established at asubstrate during processing, according to one embodiment.

FIG. 6A illustrates an example of a radio frequency (RF) waveform,according to one embodiment.

FIG. 6B illustrates an example of a pulsed radio frequency (RF)waveform, according to one embodiment.

FIG. 6C illustrates an example of a radio frequency (RF) waveform andpulsed voltage (PV) waveforms that can provided to one or moreelectrodes, according to one or more embodiments.

FIGS. 6D-6H each illustrate examples of a radio frequency (RF) waveformand a pulsed voltage (PV) waveform that can provided to one or moreelectrodes, according to one or more embodiments.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments of the disclosure provided herein include an apparatus andmethod for the plasma processing of a substrate in a processing chamber.More specifically, embodiments of this disclosure describe a biasingscheme that is configured to provide a radio frequency (RF) generated RFwaveform from an RF generator to one or more electrodes within aprocessing chamber and a pulsed-voltage (PV) waveform delivered from oneor more pulsed-voltage (PV) generators to the one or more electrodeswithin the processing chamber. In general, the generated RF waveform isconfigured to establish and maintain a plasma within the processingchamber, and the delivered PV waveform(s) are configured to establish anearly constant sheath voltage across the surface of a substrate andthus create a desirable ion energy distribution function (IEDF) at thesurface of the substrate during one or more plasma processing stepsperformed within the processing chamber. The plasma process(es)disclosed herein can be used to control the shape of IEDF and thus theinteraction of the plasma with a surface of a substrate duringprocessing. In some configurations, the plasma process(es) disclosedherein are used to control the profile of features formed in the surfaceof the substrate during processing. In some embodiments, the pulsedvoltage waveform is established by a PV generator that is electricallycoupled to a biasing electrode disposed within a substrate supportassembly disposed within a plasma processing chamber.

During some semiconductor plasma processes, ions are purposelyaccelerated towards the substrate by the voltage drop in anelectron-repelling sheath that forms over the substrate placed on top ofa substrate-support assembly 136 (FIGS. 1A-1C). While not intending tobe limiting as to the scope of the disclosure provided herein, thesubstrate support assembly 136 is often referred to herein as the“cathode assembly” or “cathode”. In some embodiments, the substratesupport assembly 136 includes a substrate support 105 and a support base107. The substrate support 105 can include an electrostatic chuck (ESC)assembly that is configured to chuck (e.g., retain) a substrate on asubstrate receiving surface 105A.

In some embodiments of the disclosure provided herein, a processingchamber is configured to provide a capacitively coupled gas discharge,such that a plasma is created by use of an RF generator assembly thatincludes an RF generator that is coupled to an RF electrode through anRF matching network (“RF match”). The RF matching network is configuredto tune the apparent load to 50Ω to minimize the reflected power andmaximize the power delivery efficiency. In some embodiments, the RFelectrode includes a metal plate that is positioned parallel to theplasma-facing surface of the substrate.

Additionally, during the plasma processing methods disclosed herein, anion-accelerating cathode sheath is generally formed during plasmaprocessing by use of a pulsed-voltage (PV) generator that is configuredto establish a pulsed-voltage waveform at one or more biasing electrodes104 (FIGS. 1A-1B) disposed within the substrate support assembly 136. Insome embodiments, the one or more biasing electrodes 104 include achucking electrode that is separated from the substrate by a thin layerof a dielectric material formed within the substrate support assembly136 (e.g., electrostatic chuck (ESC) assembly) and optionally an edgecontrol electrode that is disposed within or below an edge ring 114 thatsurrounds a substrate 103 when the substrate 103 is disposed on thesubstrate supporting surface 105A of the substrate support assembly 136.As will be discussed further below, this pulsed-voltage waveform (PVWF)can be configured to cause a nearly constant sheath voltage (e.g., adifference between the plasma potential and the substrate potential) tobe formed for a sizable portion of the PV waveform's pulse period, whichcorresponds to a single (narrow) peak containing ion energy distributionfunction (IEDF) of the ions reaching the substrate during this part ofthe pulse period, which is also referred to herein as the “ion-currentphase”.

However, as noted above, due to direct or capacitive coupling betweenthe RF generator assembly and the PV generator assembly duringprocessing, the interaction between the generated outputs from the RFgenerator and PV generator(s) will result in the power being divertedaway from the intended (plasma) load, as well as possibly causing damageto each of the RF source and the PV source(s) without the use of afiltering scheme and/or processing method disclosed herein. Thus, theapparatus and methods disclosed herein are configured to provide atleast a method of combining RF and PV power to one or more electrodes(e.g., cathode(s)) of a plasma processing chamber by coupling eachgenerator to its respective electrode through one or morewaveform-dependent filter assemblies, such that the one or morewaveform-dependent filter assemblies do not significantly impede thepower delivery provided from their respective RF and PV generators tothe plasma.

Plasma Processing Chamber Example

FIG. 1A is a schematic cross-sectional view of a processing chamber 100,in which a complex load 130 (FIGS. 3A-3B) is formed during plasmaprocessing. FIGS. 3A-3B are each examples of a simplified electricalcircuit 140 of a pulsed voltage and RF biasing scheme that can beperformed using the components found in processing chamber 100. Theprocessing chamber 100 is configured to practice one or more of thebiasing schemes proposed herein, according to one or more embodiments.In one embodiment, the processing chamber is a plasma processingchamber, such as a reactive ion etch (RIE) plasma chamber. In some otherembodiments, the processing chamber is a plasma-enhanced depositionchamber, for example a plasma-enhanced chemical vapor deposition (PECVD)chamber, a plasma enhanced physical vapor deposition (PEPVD) chamber, ora plasma-enhanced atomic layer deposition (PEALD) chamber. In some otherembodiments, the processing chamber is a plasma treatment chamber, or aplasma based ion implant chamber, for example a plasma doping (PLAD)chamber. In some embodiments, the plasma source is a capacitivelycoupled plasma (CCP) source, which includes an electrode (e.g., chamberlid 123) disposed in the processing volume facing the substrate supportassembly 136. As illustrated in FIG. 1A, an opposing electrode, such asthe chamber lid 123, which is positioned opposite to the substratesupport assembly 136, is electrically coupled to ground. However, inother alternate embodiments, the opposing electrode is electricallycoupled to an RF generator, as illustrated in FIG. 1B. In yet otherembodiments, the processing chamber may alternately, or additionally,include an inductively coupled plasma (ICP) source electrically coupledto a radio frequency (RF) power supply.

The processing chamber 100 also includes a chamber body 113 thatincludes the chamber lid 123, one or more sidewalls 122, and a chamberbase 124, which define a processing volume 129. The one or moresidewalls 122 and chamber base 124 generally include materials that aresized and shaped to form the structural support for the elements of theprocessing chamber 100, and are configured to withstand the pressuresand added energy applied to them while a plasma 101 is generated withina vacuum environment maintained in the processing volume 129 of theprocessing chamber 100 during processing. In one example, the one ormore sidewalls 122 and chamber base 124 are formed from a metal, such asaluminum, an aluminum alloy, or a stainless steel. A gas inlet 128disposed through the chamber lid 123 is used to provide one or moreprocessing gases to the processing volume 129 from a processing gassource 119 that is in fluid communication therewith. A substrate 103 isloaded into, and removed from, the processing volume 129 through anopening (not shown) in one of the one or more sidewalls 122, which issealed with a slit valve (not shown) during plasma processing of thesubstrate 103. Herein, the substrate 103 is transferred to and from asubstrate receiving surface 105A of an ESC substrate support 105 using alift pin system (not shown).

In some embodiments, an RF generator assembly 160 is configured todeliver RF power to the support base 107 disposed proximate to the ESCsubstrate support 105, and within the substrate support assembly 136.The RF power delivered to the support base 107 is configured to igniteand maintain a processing plasma 101 formed by use of processing gasesdisposed within the processing volume 129. In some embodiments, thesupport base 107 is an RF electrode that is electrically coupled to anRF generator 118 via an RF matching circuit 161 and a first filterassembly 162, which are both disposed within the RF generator assembly160. In some embodiments, the plasma generator assembly 160 and RFgenerator 118 are used to ignite and maintain a processing plasma 101using the processing gases disposed in the processing volume 129 andfields generated by the RF power provided to the support base 107 by theRF generator 118. The processing volume 129 is fluidly coupled to one ormore dedicated vacuum pumps, through a vacuum outlet 120, which maintainthe processing volume 129 at sub-atmospheric pressure conditions andevacuate processing and/or other gases, therefrom. A substrate supportassembly 136, disposed in the processing volume 129, is disposed on asupport shaft 138 that is grounded and extends through the chamber base124. However, in some embodiments, the RF generator assembly 160 isconfigured to deliver RF power to the biasing electrode 104 disposed inthe substrate support 105 versus the support base 107.

The substrate support assembly 136, as briefly discussed above,generally includes a substrate support 105 (e.g., ESC substrate support)and support base 107. In some embodiments, the substrate supportassembly 136 can additionally include an insulator plate 111 and aground plate 112, as is discussed further below. The substrate support105 is thermally coupled to and disposed on the support base 107. Insome embodiments, the support base 107 is configured to regulate thetemperature of the substrate support 105, and the substrate 103 disposedon the substrate support 105, during substrate processing. In someembodiments, the support base 107 includes one or more cooling channels(not shown) disposed therein that are fluidly coupled to, and in fluidcommunication with, a coolant source (not shown), such as a refrigerantsource or water source having a relatively high electrical resistance.In some embodiments, the substrate support 105 includes a heater (notshown), such as a resistive heating element embedded in the dielectricmaterial thereof. Herein, the support base 107 is formed of a corrosionresistant thermally conductive material, such as a corrosion resistantmetal, for example aluminum, an aluminum alloy, or a stainless steel andis coupled to the substrate support with an adhesive or by mechanicalmeans.

The support base 107 is electrically isolated from the chamber base 124by the insulator plate 111, and the ground plate 112 is interposedbetween the insulator plate 111 and the chamber base 124. In someembodiments, the processing chamber 100 further includes a quartz pipe110, or collar, that at least partially circumscribes portions of thesubstrate support assembly 136 to prevent corrosion of the ESC substratesupport 105 and, or, the support base 107 from contact with corrosiveprocessing gases or plasma, cleaning gases or plasma, or byproductsthereof. Typically, the quartz pipe 110, the insulator plate 111, andthe ground plate 112 are circumscribed by a liner 108. Herein, a plasmascreen 109 approximately coplanar with the substrate receiving surfaceof the ESC substrate support 105 prevents plasma from forming in avolume between the liner 108 and the one or more sidewalls 122.

The substrate support 105 is typically formed of a dielectric material,such as a bulk sintered ceramic material, such as a corrosion resistantmetal oxide or metal nitride material, for example aluminum oxide(Al₂O₃), aluminum nitride (AlN), titanium oxide (TiO), titanium nitride(TiN), yttrium oxide (Y₂O₃), mixtures thereof, or combinations thereof.In embodiments herein, the substrate support 105 further includes abiasing electrode 104 embedded in the dielectric material thereof. Inone configuration, the biasing electrode 104 is a chucking pole used tosecure (chuck) the substrate 103 to a substrate receiving surface 105Aof the substrate support 105, also referred to herein as an ESCsubstrate support, and to bias the substrate 103 with respect to theprocessing plasma 101 using one or more of the pulsed-voltage biasingschemes described herein. Typically, the biasing electrode 104 is formedof one or more electrically conductive parts, such as one or more metalmeshes, foils, plates, or combinations thereof. In some embodiments, thebiasing electrode 104 is electrically coupled to a chucking module 116,which provides a chucking voltage thereto, such as static DC voltagebetween about −5000 V and about 5000 V, using an electrical conductor,such as the coaxial transmission line 106 (e.g., a coaxial cable). Aswill be discussed further below, the chucking module 116 includes biascompensation circuit elements 116A (FIGS. 3A-3B), a DC power supply 155,and a blocking capacitor 153. A chucking module blocking capacitor,which is also referred to herein as the blocking capacitor 153, isdisposed between the output of a pulsed-voltage waveform generator(PVWG) 150 and the biasing electrode 104.

The biasing electrode 104 is spaced apart from the substrate receivingsurface 105A of the substrate support 105, and thus from the substrate103, by a layer of dielectric material of the substrate support 105.Depending on the type of electrostatic chucking method utilized withinthe substrate support 105 to retain a substrate 103 during processing,such as a coulombic ESC or a Johnsen-Rahbek ESC, the effective circuitelements used to model the electrical coupling of the biasing electrode104 to the plasma 101 will vary. FIGS. 3C and 3D illustrate theeffective circuit elements 191 created when a coulombic ESC or aJohnsen-Rahbek ESC, respectively, are utilized during plasma processing.In general, a parallel plate like structure is formed by the biasingelectrode 104 and the layer of the dielectric material that cantypically have an effective capacitance C_(E) of between about 5 nF andabout 50 nF. Typically, the layer of dielectric material (e.g., aluminumnitride (AlN), aluminum oxide (Al₂O₃), etc.) has a thickness betweenabout 0.1 mm and about 1 mm, such as between about 0.1 mm and about 0.5mm, for example about 0.3 mm. Herein, the biasing electrode 104 iselectrically coupled to the output of the pulsed-voltage waveformgenerator (PVWG) 150 using the external conductor, such as thetransmission line 106, which is disposed within the support shaft 138.In some embodiments, the dielectric material and layer thickness can beselected so that the chuck capacitance C_(ESC) of the layer ofdielectric material is between about 5 nF and about nF, such as betweenabout 7 and about 10 nF, for example.

In a more complex model of the Johnsen-Rahbek ESC illustrated in FIG.3D, the circuit model includes the combination of the ESC dielectricmaterial chuck capacitance C_(ESC), ESC dielectric material resistanceR_(CER), gap capacitance C_(abt), substrate capacitance C_(sub), andsubstrate resistance R_(sub) as shown. The gap capacitances C_(abt) willgenerally account for gas containing spaces above and below a substratethat is positioned on the substrate support 105. It is expected that thegap capacitance C_(abt) has a capacitance in the same range as the chuckcapacitance C_(ESC).

In some applications, since the substrate 103 is typically made out of athin layer of a semiconductor material and/or dielectric material, thesubstrate 103 can be considered to be electrically a part of the ESCdielectric layer disposed between the biasing electrode 104 and thesubstrate receiving surface 105A. Thus, in some applications, the chuckcapacitance C_(ESC) is approximated by the combined series capacitanceof the ESC and the substrate (i.e., substrate capacitance C_(sub)).However, in the coulombic chuck case, since the substrate capacitanceC_(sub) is typically very large (>10 nF), or the substrate may beconductive (infinite capacitance), the series capacitance is determinedprimarily by the capacitance C_(ESC). In this case, the effectivecapacitance C_(E), as illustrated in FIG. 3C, is effectively equal tothe chuck capacitance C_(ESC). In the case of a “Johnsen-Rahbek ESC”,the ESC dielectric layer is “leaky”, in that it is not a perfectinsulator and has some conductivity, since, for example, the dielectricmaterial may be a doped aluminum nitride (AlN) having a permittivity (c)of about 9. However, the effective capacitance of a Johnsen-Rahbek ESCshould be similar to a coulombic chuck. In one example, the volumeresistivity of the dielectric layer within a Johnsen-Rahbek ESC is lessthan about 10¹² ohms-cm (Ω-cm), or less than about 10¹⁰ Ω-cm, or even ina range between 10^(8 Ω-cm and) 10^(12 Ω-cm.)

The substrate support assembly 136 further includes an edge controlelectrode 115 that is positioned below the edge ring 114 and surroundsthe biasing electrode 104 so that when biased, due to its positionrelative to the substrate 103, it can affect or alter a portion of thegenerated plasma 101 that is at or outside of the edge of the substrate103. The edge control electrode 115 can be biased by use of apulsed-voltage waveform generator (PVWG) 150 that is different from thepulsed-voltage waveform generator (PVWG) 150 that is used to bias thebiasing electrode 104. In one configuration, a first PV waveformgenerator 150 of a first PV source assembly 196 is configured to biasthe biasing electrode 104, and a second PV waveform generator 150 of asecond PV source assembly 197 is configured to bias the edge controlelectrode 115. In one embodiment, the edge control electrode 115 ispositioned within a region of the substrate support 105, as shown inFIG. 1A. In general, for processing chambers 100 that are configured toprocess circular substrates, the edge control electrode 115 is annularin shape, is made from a conductive material and configured to surroundat least a portion of the biasing electrode 104, as shown in FIG. 1A-1B.In some embodiments, as illustrated in FIG. 1A, the edge controlelectrode 115 includes a conductive mesh, foil or plate that is disposeda similar distance (i.e., Z-direction) from the surface 105A of thesubstrate support 105 as the biasing electrode 104. In some otherembodiments, the edge control electrode 115 includes a conductive mesh,foil or plate that is positioned on or within a region of the dielectricpipe 110 (e.g., AlN, or Al₂O₃), which surrounds at least a portion ofthe biasing electrode 104 and/or the substrate support 105, as shown inFIG. 1B. Alternately, in some other embodiments, the edge controlelectrode 115 is positioned within or is coupled to the edge ring 114,which is disposed adjacent to the substrate support 105. In thisconfiguration, the edge ring 114 is formed from a semiconductor ordielectric material (e.g., AlN, Al₂O₃, etc.).

Referring to FIG. 1B, in some embodiments, the substrate support 105further includes a secondary electrode 104L (e.g., metal mesh, foil orplate) that is electrically coupled to the biasing electrode 104 by useof a plurality of conductive vias 114V. One or more of the vias 114Vhave a first end that is in electrical contact with the biasingelectrode 104 and a second end that is in electrical contact with thesecondary electrode 104L. The secondary electrode 104L, which isdisposed below the biasing electrode 104, is aligned, positioned andsized to improve the control of the plasma sheath and/or plasmauniformity over the surface of the substrate 103 during processing. Insome configurations, as shown in FIG. 1B, the edge control electrode 115is positioned adjacent to the secondary electrode 104L so that when usedin combination, the biasing electrode 104, secondary electrode 114L andedge control electrode 115 will desirably alter the generated plasma 101that is at or outside of the edge of the substrate 103.

Referring to FIGS. 1A and 1B, the support base 107 is spaced apart fromthe biasing electrode 104 by a portion of dielectric material. Theportion of dielectric material in some configurations is the dielectricmaterial used to form the substrate support 105, and extends from thebackside of the substrate support 105 to the biasing electrode 104. Theportion of dielectric material of the substrate support 105 has asupport base capacitance Ca that is in series with the ESC capacitanceC_(E), as schematically illustrated in FIGS. 3A and 3B. In someembodiments, the thickness of the portion of the dielectric materialdisposed between the support base 107 and the biasing electrode 104 isgreater than the thickness of the dielectric material disposed betweenthe biasing electrode 104 and the substrate 103, wherein the dielectricmaterials are the same material and/or form part of the substratesupport 105. In one example, the portion of a dielectric material of thesubstrate support 105 (e.g., Al₂O₃ or AlN) disposed between support base107 and the biasing electrode 104 is greater than 1 mm thick, such asbetween about 1.5 mm and about 20 mm thick.

Generally, a low pressure formed in the processing volume 129 of theprocessing chamber 100 results in poor thermal conduction betweensurfaces of hardware components disposed therein, such as between thedielectric material of the substrate support 105 and the substrate 103disposed on the substrate receiving surface thereof, which reduces thesubstrate support's effectiveness in heating or cooling the substrate103. Therefore, in some processes, a thermally conductive inert heattransfer gas, typically helium, is introduced into a volume (not shown)disposed between a non-device side surface of the substrate 103 and thesubstrate receiving surface 105A of the substrate support 105 to improvethe heat transfer therebetween. The heat transfer gas, provided by aheat transfer gas source (not shown), flows to the backside volumethrough a gas communication path (not shown) disposed through thesupport base 107 and further disposed through the substrate support 105.

The processing chamber 100 further includes a controller 126, which isalso referred to herein as a processing chamber controller. Thecontroller 126 herein includes a central processing unit (CPU) 133, amemory 134, and support circuits 135. The controller 126 is used tocontrol the process sequence used to process the substrate 103 includingthe substrate biasing methods described herein. The CPU 133 is ageneral-purpose computer processor configured for use in an industrialsetting for controlling processing chamber and sub-processors relatedthereto. The memory 134 described herein, which is generallynon-volatile memory, may include random access memory, read only memory,floppy or hard disk drive, or other suitable forms of digital storage,local or remote. The support circuits 135 are conventionally coupled tothe CPU 133 and comprise cache, clock circuits, input/output subsystems,power supplies, and the like, and combinations thereof. Softwareinstructions (program) and data can be coded and stored within thememory 134 for instructing a processor within the CPU 133. A softwareprogram (or computer instructions) readable by CPU 133 in the controller126 determines which tasks are performable by the components in theprocessing chamber 100. Preferably, the program, which is readable byCPU 133 in the controller 126, includes code, which when executed by theprocessor (CPU 133), perform tasks relating to the monitoring andexecution of the electrode biasing scheme described herein. The programwill include instructions that are used to control the various hardwareand electrical components within the processing chamber 100 to performthe various process tasks and various process sequences used toimplement the electrode biasing scheme described herein.

During processing, the PV generators 314 within the PV waveformgenerators 150 of the first PV source assembly 196 and the second PVsource assembly 197 establishes a pulsed voltage waveform on a load(e.g., the complex load 130) disposed with the processing chamber 100.While not intending to be limiting as to the disclosure provided herein,and to simplify the discussion, the components within the second PVsource assembly 197, which are used to bias the edge control electrode115, are not schematically shown in FIGS. 3A-3B. The overall control ofthe delivery of the PV waveform from each of the PV waveform generators150 is controlled by use of signals provided from the controller 126. Inone embodiment, as illustrated in FIG. 3A, the PV waveform generator150A is configured to maintain a predetermined, substantially constantpositive voltage across its output (i.e., to ground) during regularlyrecurring time intervals of a predetermined length, by repeatedlyclosing and opening its internal switch S₁ at a predetermined rate.Alternately, in one embodiment, as illustrated in FIG. 3B, a PV waveformgenerator 150B maintains a predetermined, substantially constantnegative voltage across its output (i.e., to ground) during regularlyrecurring time intervals of a predetermined length, by repeatedlyclosing and opening its internal switch S₁ at a predetermined rate. InFIGS. 3A-3B, the PV waveform generator 150A, 150B is reduced to aminimal combination of the components that are important forunderstanding of its role in establishing a desired pulsed voltagewaveform at the biasing electrode 104. Each PV waveform generator 150will include a PV generator 314 (e.g., DC power supply) and one or moreelectrical components, such as high repetition rate switches, capacitors(not shown), inductors (not shown), fly back diodes (not shown), powertransistors (not shown) and/or resistors (not shown), that areconfigured to provide a PV waveform to an output 350, as schematicallyillustrated in FIGS. 3A-3B. An actual PV waveform generator 150, whichcan be configured as a nanosecond pulse generator, may include anynumber of internal components and may be based on a more complexelectrical circuit than what is illustrated in FIGS. 3A-3B. Theschematic diagrams of FIGS. 3A-3B each provide only a functionallyequivalent representation of the components of the PV waveform generator150 and its electrical circuitry, in as much as is required to explainthe fundamental principle of its operation, its interaction with theplasma in the processing volume, and its role in establishing a pulsedvoltage waveform, such as the input pulsed voltage waveform 401, 431,441 (FIGS. 4A-4C) at the biasing electrode 104. As can be inferred froma schematic diagram shown in FIGS. 3A-3B, when the switch S₁ moves fromthe open (Off) to the closed (On) position, it connects the output ofthe PV waveform generator 150 to its PV generator 314 that produces asubstantially constant output voltage. The PV waveform generator 150 maybe primarily used as a charge injector (current source), and not as aconstant voltage source; therefore it is not necessary to imposestringent requirements on the stability of the output voltage, in thatit can vary in time even when the switch remains in the closed (On)position. Further, in some configurations, the PV generator 314 isfundamentally a sourcing, but not a sinking supply, in that it onlypasses a current in one direction (e.g., the output can charge, but notdischarge a capacitor). Additionally, when the switch S₁ remains in theopen (Off) position, the voltage (Vo), across the output of the PVwaveform generator 150 is not controlled by the PV generator 314 and isinstead determined by the interaction of its internal components withother circuit elements.

A current-return output stage 314A has one end connected to ground, andanother end connected to a connection point (i.e., one side of agenerator output coupling assembly (not shown)) at the output of the PVwaveform generator 150. The current-return output stage 314A can includethe following elements: a resistor, a resistor and an inductor connectedin series, a switch S₂, and/or a more complex combination of electricalelements, including parallel capacitors, which permits a positivecurrent flow towards the ground.

Transmission line 131, which forms part of the PV transmission line 157(FIGS. 1A-1B), electrically connects the output 350 of the PV waveformgenerator 150 to the second filter assembly 151. While the discussionbelow primarily discusses the PV transmission line 157 of the first PVsource assembly 196, which is used to couple a PV waveform generator 150to the biasing electrode 104, the PV transmission line 158 of the secondPV source assembly 197, which couples a PV waveform generator 150 to theedge control electrode 115, will include the same or similar components.Therefore, in general, the output 350 of the PV waveform generator 150is the end, where the output of the PV pulse generator 314 is connectedthrough the internal electrical conductor to the output 350 and to thecurrent-return output stage 314A. The transmission line 131 connects agenerator output coupling assembly 181 (FIG. 1C), which is positioned atthe output 350 of the PV waveform generator 150, to the second filterassembly 151. The electrical conductor(s) within the various parts ofthe PV transmission line 157, 158 may include: (a) a coaxialtransmission line (e.g., coaxial line 106), which may include a flexiblecoaxial cable that is connected in series with a rigid coaxialtransmission line, (b) an insulated high-voltage corona-resistant hookupwire, (c) a bare wire, (d) a metal rod, (e) an electrical connector, or(f) any combination of electrical elements in (a)-(e). The externalconductor portion (e.g., first electrical conductor) of the PVtransmission line 157, such as the portion of PV transmission line 157within the support shaft 138 and the biasing electrode 104, will havesome combined stray capacitance C_(stray) (FIGS. 3A-3B) to ground. Whilenot shown in the figures, the external conductor portion (e.g., secondelectrical conductor) of the PV transmission line 158 and the edgecontrol electrode 115 will also have some combined stray capacitanceC_(stray) to ground. The internal electrical conductor of the PVwaveform generator 150 may include the same basic elements as theexternal electrical conductor. In most practical applications, thetransmission line 131 will include a line inductance 159 which caninclude a portion that is created by the internal components of the PVwaveform generator 150 (i.e., left side of the generator output couplingassembly 181 (FIGS. 3A-3B)) and/or a portion that is created by theexternal line/cables (i.e., right side of the generator output couplingassembly 181) that connect the PV waveform generator 150 to the secondfilter assembly 151.

Referring back to FIG. 1A, the processing chamber 100 includes a chamberlid 123 that is grounded. In this configuration, which is generallydifferent from conventional plasma processing chamber designs, the RFpower is instead delivered through the substrate support. Thus, bycoupling the RF generator 118 to the support base 107, the entire bodyof the ESC, which is functionally part of the cathode assembly, enablesthe top electrode to be grounded and allows the current-return area tobe maximized. For plasma processes that utilize RF power delivery and PVwaveform delivery, maximizing the grounded surface area within theplasma processing chamber, and hence the current-return area, minimizesthe plasma potential jump during the ESC-recharging/sheath-collapsephase of the PV waveform cycle generated by the output of the PVwaveform generator 150, which are discussed further below. Thus, theapparatus and methods provided herein will minimize the power losses tochamber walls and improves the plasma processing efficiency. The RFpower and PV pulsed waveform delivery methods described herein alsoprovides certain process benefits as they impact and allow for animproved control of the plasma properties and radical production.However, as noted above, there is a strong capacitive coupling betweenthe support base 107 and the biasing electrode 104 through the ESCceramic layer as well as between the RF transmission line 167 and PVtransmission line 157, so when both types of power are delivered throughthe substrate support assembly 136 (i.e., cathode assembly), eachgenerator will induce the current through the other, resulting in thepower being diverted away from the intended (plasma) load as well as apossible damage to both generators.

In another alternate chamber lid 123 configuration, which can be usedwith one or more of the other embodiments disclosed herein, the chamberlid 123 (i.e., opposing electrode) is electrically isolated from the oneor more sidewalls 122 and is electrically coupled to an RF generator 118through a plasma generator assembly 160, as shown in FIG. 1B. In thisconfiguration, the chamber lid 123 can be driven by a RF generator 118to ignite and maintain a processing plasma 101 within the processingvolume 129. In one example, a RF generator 118 is configured to providean RF signal at an RF frequency greater than about 300 kHz to thechamber lid 123, such as between about 300 kHz and 60 MHz, or even afrequency in range from about 2 MHz to about 40 MHz.

Biasing Subsystem Assembly

FIG. 1C is a schematic diagram of the processing chamber 100 thatincludes a biasing subsystem assembly 170 that is configured to encloseand separately isolate various electrical components used to control,generate and deliver the radio frequency waveform(s) and thepulsed-voltage waveform(s) to the one or more electrodes within theprocessing chamber 100, such as the substrate support assembly 136. Dueto at least to the configuration of and positioning of the biasingsubsystem assembly 170 within a process chamber 100 a more repeatableand efficient delivery of the generated RF and PV waveforms can beachieved during processing. It is believed that the use of the biasingsubsystem assembly 170 within each of a plurality of similarlyconfigured process chambers can also help reduce process resultvariability found in a substrate-processing facility containing manyprocessing chambers and other substrate-processing facilities around theworld that contain many processing chambers.

The biasing subsystem assembly 170 will generally include apulsed-voltage generating unit enclosure 172 and a junction boxenclosure 169. The biasing subsystem assembly 170 will generally includeactive power and voltage sources, as well as electrical circuits thatinclude passive components. The active sources may include one or morepulsed voltage waveform generators, one or more RF generators and/or oneor more DC power sources. The passive components within the electricalcircuits may include resistors, capacitors, inductors and diodes. Whenin use, the biasing subsystem assembly 170 can be used to combinedifferent kinds of power sources so that their output can be applied tothe same load (e.g., complex load 130). The load may include the plasma101 formed in the processing chamber 100, the cathode sheath, cathodeand its power delivery system (e.g., transmission line(s)) as well asstray inductive and capacitive elements.

In some embodiments, the junction box enclosure 169 includes one or morebias compensation module compartments 171 and a radio frequency (RF)filter compartment 173. In some embodiments, the biasing subsystemassembly 170 also includes an RF delivery enclosure 174. Each of thecompartments 171, 172, and 173 and the RF delivery enclosure 174 includeone or more walls 171A, 172A, 173A and 174A, respectively, that are eachconfigured to at least partially enclose, separate and isolate theirinternal electrical components from the electrical components found inadjacently positioned enclosures and an environment outside of theprocess chamber 100. Typically, only a single wall is used to isolateadjacent compartments from each other. While FIGS. 1C and 1Dschematically illustrates, in some regions, two walls that positioned ina directly adjacent relationship, this is not intended to be limiting asto scope of the disclosure provided herein, since a single wall maybeused in place of two separate abutting walls. The biasing subsystemassembly 170 is positioned on or is coupled to one or more of the wallsof the process chamber 100, such as the base 124, so as to rigidlymount, repeatably define the distance between components, and avoidstrain on any connections provided between the biasing subsystemassembly 170 and the other components (e.g., connections to thesubstrate support assembly 136) within the process chamber 100. In someembodiments, a surface of the biasing subsystem assembly 170 (e.g.,exposed surface of walls 173A) is positioned adjacent to one or more ofthe walls of the process chamber 100 (e.g., base 124). In someembodiments, an exposed surface (e.g., surface of wall 173A) of thebiasing subsystem assembly 170 is positioned a distance 124A (FIG. 1C)of less than 24 inches, such as less than 12 inches, or even less than 6inches from the base 124. In one example, the exposed surface of walls173A are directly coupled to a lower surface of the base 124. It isbelieved that by optimizing the routing and minimizing the connectionlengths of the current carrying elements that interconnect theelectrical components within the compartments 171, 172, and 173 and/orRF delivery enclosure 174 of the biasing subsystem assembly 170, such asthe connections between the bias compensation compartment components andthe components in the radio frequency filter compartment 173, the formedstray inductance and stray capacitance in each of these areas of thesystem can be minimized. In practice, the biasing subsystem assembly 170can be used to significantly reduce oscillations in the generated andestablished waveforms, and thus improve the integrity and repeatabilityof the high-voltage signals provided to the electrodes within theprocess chamber 100, such as the electrodes within the substrate supportassembly 136.

The pulsed-voltage generating unit enclosure 172 includes at least onePV waveform generator 150 that is isolated from the electricalcomponents found in the bias compensation module compartment 171, theradio frequency filter compartment 173 and the RF delivery enclosure 174by at least the wall(s) 172A. The wall(s) 172A can include a groundedsheet metal box (e.g., aluminum or SST box) that is configured tosupport and isolate the one or more PV waveform generators 150 from anyelectromagnetic interference generated by the components within the RFdelivery enclosure 174 and/or external to the process chamber 100. At aninterface between the pulsed-voltage generating unit enclosure 172 andthe bias compensation module compartment 171, a generator outputcoupling assembly 181 is used to connect the output 350 of a PV waveformgenerator 150 to a first portion of the transmission line 131 and theelectrical components (e.g., blocking capacitor 153) disposed within thebias compensation module compartment 171. The term “coupling assembly”,as used herein, generally describes one or more electrical components,such as one or more electrical connectors, discrete electrical elements(e.g., capacitor, inductor, and resistor) and/or conductive elementsthat are configured to connect the current carrying elements thatelectrically couple two or more electrical components together.

The one or more bias compensation module compartments 171 includes thebias compensation circuit elements 116A (FIGS. 3A-3B) and a blockingcapacitor 153 that are isolated from the electrical components found inthe pulsed-voltage generating unit enclosure 172, the radio frequencyfilter compartment 173 and the RF delivery enclosure 174 by at least thewall(s) 171A. In one embodiment, the bias compensation circuit elements116A are coupled to an externally positioned DC power supply 155 by useof bias compensation module compartment DC source coupling assembly 185that is formed at a wall 171A. Alternately, in one embodiment (notshown), the bias compensation circuit elements 116A and DC power supply155 are both disposed within a bias compensation module compartment 171and enclosed by a wall 171A. The wall(s) 171A can include a groundedsheet metal box that is configured to isolate the components within thebias compensation module compartment 171 from any electromagneticinterference generated by the components within the pulsed-voltagegenerating unit enclosure 172, the RF delivery enclosure 174 and/orexternal to the process chamber 100. At an interface between the biascompensation module compartment 171 and the radio frequency filtercompartment 173, a bias compensation module compartment output couplingassembly 182 is used to connect the bias compensation circuit elements116A, DC power supply 155 and blocking capacitor 153 to a second portionof the transmission line 131 and the electrical components (e.g., secondfilter assembly 151) disposed within the radio frequency filtercompartment 173.

The radio frequency filter compartment 173 includes one or more secondfilter assemblies 151 and chamber interconnecting components that areisolated from the electrical components found in the pulsed-voltagegenerating unit enclosure 172, the one or more bias compensation moduleenclosures 171, and the RF delivery enclosure 174 by at least thewall(s) 173A. The wall(s) 173A can include a grounded sheet metal boxthat is configured to isolate the components within the radio frequencyfilter compartment 173 from any electromagnetic interference generatedby the components within the pulsed-voltage generating unit enclosure172, the RF delivery enclosure 174 and/or external to the processchamber 100. At an interface between the radio frequency filtercompartment 173 and the base 124 of the process chamber 100, a cathodecoupling assembly 183 is used to connect the output connection(s) of theradio frequency filter compartment 173 to a portion of the PVtransmission lines 157, 158 that electrically connect the biasingsubsystem assembly 170 to one of the electrodes within the processchamber 100, such as the electrodes within the substrate supportassembly 136.

The RF delivery enclosure 174 includes the RF matching circuit 161, thefirst filter assembly 162, optionally the RF generator 118, and otherchamber interconnecting components that are isolated from the electricalcomponents found in the pulsed-voltage generating unit enclosure 172 andthe one or more bias compensation module enclosures 171 by at least thewall(s) 174A. The wall(s) 174A can include a grounded sheet metal boxthat is configured to isolate the components within the RF deliveryenclosure 174 from any electromagnetic interference generated by thecomponents within the pulsed-voltage generating unit enclosure 172and/or external to the process chamber 100. At an interface between theRF delivery enclosure 174 and the base 124 of the process chamber 100, acathode coupling assembly 184 is used to connect the outputconnection(s) of RF delivery enclosure 174 to a portion of the RFtransmission line 167 that electrically connect the RF deliveryenclosure 174 of the biasing subsystem assembly 170 to one of theelectrodes within the process chamber 100, such as the electrodes withinthe substrate support assembly 136. The external conductor portion(e.g., third electrical conductor) of the RF transmission line 167, suchas the portion of the RF transmission line 167 within the support shaft138 and the support base 107 will have some combined stray capacitanceC_(stray) to ground.

FIG. 1D is a schematic diagram of the processing chamber 100 thatincludes an alternate version of the biasing subsystem assembly 170illustrated in FIG. 1C. As shown in FIG. 1D, the first filter assembly162 has been removed from RF delivery enclosure 174 and repositionedwithin the radio frequency filter compartment 173. In thisconfiguration, the RF generator 118 is configured to deliver an RFwaveform through the RF matching circuit 161, cathode coupling assembly184, a first RF coupling assembly 186, the first filter assembly 162, asecond RF coupling assembly 187, the RF transmission line 167 and thento an electrode with the substrate support assembly 136. In thisconfiguration, the radio frequency filter compartment 173 includes oneor more second filter assemblies 151, the first filter assembly 162, andother chamber interconnecting components.

Plasma Processing Biasing Schemes and Processes

FIG. 2 is a simplified schematic diagram of a biasing scheme that can beused with the process chamber illustrated in FIG. 1A or 1B. As shown inFIG. 2 , the RF generator 118 and PV waveform generators 150 areconfigured to deliver an RF waveform and pulsed-voltage waveforms,respectively, to one or more electrodes disposed within the chamber body113 of the processing chamber 100. In one embodiment, the RF generator118 and PV waveform generators 150 are configured to simultaneouslydeliver an RF waveform and pulsed-voltage waveform(s) to one or moreelectrodes disposed within the substrate support assembly 136. In onenon-limiting example, as discussed above, the RF generator 118 and a PVwaveform generator 150 are configured to deliver an RF waveform andpulsed-voltage waveform to the support base 107 and biasing electrode104, respectively, which are both disposed in the substrate supportassembly 136. In another example, the RF generator 118, a first PVwaveform generator 150 and a second PV waveform generator 150 areconfigured to deliver an RF waveform, a first pulsed-voltage waveformand a second pulsed-voltage waveform to the support base 107, thebiasing electrode 104 and the edge control electrode 115, respectively,which are all disposed in the substrate support assembly 136.

As illustrated in FIG. 2 , the RF generator 118 is configured to providea sinusoidal RF waveform to the one or more electrodes disposed in thechamber body 113 by delivering the RF signal, which includes thesinusoidal RF waveform 601 (FIGS. 6A-6G), through the plasma generatorassembly 160, which includes the RF matching circuit 161 and the firstfilter assembly 162. Additionally, each of the PV waveform generators150 are configured to provide a PV waveform, which typically includes aseries of voltage pulses (e.g., nanosecond voltage pulses), to the oneor more electrodes disposed in the chamber body 113 by establishing a PVwaveform 401 (FIGS. 4A, 5A), 441 (FIG. 5B), or 431 (FIG. 5C) at thebiasing electrode 104 through the second filter assembly 151. Thecomponents within the chucking module 116 can be optionally positionedbetween each PV waveform generator 150 and the second filter assembly151.

As briefly discussed above, FIGS. 3A-3B are each examples of afunctionally equivalent, simplified electrical circuit 140 of the pulsedvoltage and RF biasing scheme proposed herein, which also includes arepresentation of the plasma in the process volume. FIG. 3A depicts asimplified electrical circuit 140 of a pulsed voltage and RF biasingscheme that utilizes a PV waveform generator 150, within the first PVsource assembly 196, that is configured to provide a positive voltageduring a portion of the process of establishing the PV waveform at thebiasing electrode 104, such as PV waveform 431 (FIG. 5C). FIG. 3Bdepicts a simplified electrical circuit 140 of a pulsed voltage and RFbiasing scheme that utilizes a PV waveform generator 150, within thefirst PV source assembly 196, that is configured to provide a negativevoltage during a portion of the process of establishing the PV waveformat the biasing electrode 104, such as PV waveform 401 (FIGS. 4A and 5A).These circuits illustrate a simplified model of the interaction of apulsed-voltage waveform generator 150 of the first PV source assembly196 and RF generator 118 within the processing chamber 100, andgenerally illustrate the basic elements used during operation of theprocess chamber 100. For clarity purposes, the following definitions areused throughout this disclosure: (1) unless a reference is specified,all potentials are referenced to ground; (2) the voltage at any physicalpoint (like a substrate or a biasing electrode) is likewise defined asthe potential of this point with respect to ground (zero potentialpoint); (3) the cathode sheath is implied to be an electron-repelling,ion-accelerating sheath that corresponds to a negative substratepotential with respect to plasma; (4) the sheath voltage (also referredto sometimes as “sheath voltage drop”), V_(sh), is defined as theabsolute value of the potential difference between the plasma and theadjacent surface (e.g. of the substrate or the chamber wall); and (5)the substrate potential is the potential at the substrate surface facingthe plasma.

The complex load 130 illustrated in FIGS. 3A-3B is shown as a standardelectrical plasma model that represents the processing plasma 101 asthree series elements. The first element being an electron-repellingcathode sheath (which we sometimes also refer to as the “plasma sheath”or just the “sheath”) adjacent to the substrate 103. The cathode sheathis represented in FIGS. 3A-3B by a conventional three-part circuitelement comprising: (a) the diode D_(SH), which when open represents thesheath collapse, (b) the current source I_(i), representing the ioncurrent flowing to the substrate in the presence of the sheath, and (c)the capacitor C_(SH) (e.g., ˜100-300 pF), which represents the sheathfor the main portion of the biasing cycle (i.e., ion current phase ofthe PV waveform), during which the ion acceleration and the etchingoccur. The second element being a bulk plasma, which is represented by asingle resistor R_(plasma) (e.g., resistor 146=˜5-10 Ohms). The thirdelement being an electron-repelling wall sheath forming at the chamberwalls. The wall sheath is likewise represented in FIG. 3 by a three-partcircuit element comprising: (a) the diode D_(wall), (b) the currentsource I_(iwall) representing the ion current to the wall, and (c) thecapacitor C_(wall) (e.g., ˜5-10 nF), which represents the wall sheathprimarily during the ESC recharging phase of the PV waveform (describedlater in the text). The interior surface of the grounded metal walls canalso be considered be coated with a thin layer of a dielectric material,which is represented in FIG. 3 by a large capacitor C_(coat) (e.g.,˜300-1000 nF).

As illustrated in FIG. 3A-3B, the RF generator 118 is configured toprovide an RF signal to the support base 107, and eventually the complexload 130, by delivering the generated RF power through the first filterassembly 162, the RF matching circuit 161, line inductance Lune, supportbase capacitance C_(CL), and effective capacitance C_(E). In oneembodiment, the RF matching circuit 161 includes a series inductanceelement L_(SER), and an adjustable series capacitance element CSER andan adjustable shunt capacitance element C_(Shunt) that can be controlledby input from the controller 126. In some embodiments, the RF matchingcircuit 161 may alternately be formed by use of other circuit elementconfigurations, such as L network, pi network, or transmatch circuits,for example. As noted above, the RF matching circuit 161 is generallyconfigured to tune the apparent load to 50Ω to minimize the reflectedpower generated by the delivery of the RF signal from the RF generator118 and maximize its power delivery efficiency. In some embodiments, theRF matching circuit 161 is optional, and in these cases other RF signalmatching techniques may be used (e.g., variable frequency tuning) duringa plasma processing of a substrate to avoid the inefficient deliveringRF power to the complex load 130.

The first filter assembly 162, also referred to herein as the pulsedvoltage filter assembly, includes one or more electrical elements thatare configured to substantially prevent a current generated by theoutput of the PV waveform generator 150 from flowing through the RFtransmission line 167 and damaging the RF generator 118. The firstfilter assembly 162 acts as a high impedance (e.g., high Z) to the PVsignal generated from the PV pulse generator 314 within the PV waveformgenerator 150, and thus inhibits the flow of current to the RF generator118. In one embodiment, the first filter assembly 162 includes ablocking capacitor C_(BC), which is disposed between the RF matchingcircuit 161 and the RF generator 118. In this configuration, the RFmatching element 161 is configured to compensate for the capacitance ofthe blocking capacitor C_(BC) as it tunes the load apparent to the RFgenerator 118. In one example, to prevent a nanosecond PV waveform(e.g., pulse period 10-100 ns) provided from the PV waveform generator150 from damaging the RF generator 118 the first filter assembly 162includes a 35-100 pF capacitor. In another example, the first filterassembly 162 includes a blocking capacitor C_(BC) that has a capacitancethat is less than 50 pF.

In some embodiments, it may be desirable to utilize two or more sets ofRF generators 118 and RF plasma generator assemblies 160 that are eachconfigured to separately provide RF power at different RF frequencies tothe support base 107, or other electrodes within the substrate supportassembly 136. In one example, a first RF generator 118A (not shown) andfirst RF plasma generator assembly 160A (not shown) are configured toprovide an RF signal at an RF frequency between about 300 kHz and 13.56MHz to the support base 107 and a second RF generator 118B (not shown)and second RF plasma generator assembly 1608 (not shown) are configuredto provide an RF signal at an RF frequency of about 40 MHz or greater tothe support base 107. In this example, each of the RF generatorassemblies 160A, 160B will include a similarly configured first filterassembly 162 (e.g., includes a blocking capacitor having a capacitanceC_(BC)) that is adapted to prevent a current generated by the output ofthe PV waveform generator 150 from flowing through the respectivetransmission lines and damaging each of the respective RF generators. Inaddition, each of the RF generator assemblies 160A, 160B may alsoinclude a separate RF filter assembly, such as the second filterassembly 151 that is connected in series with their respective RFgenerator assembly and is configured to block the other RF frequenciesdelivered from the other RF generator assemblies to additionally preventan RF currents generated by the output of the other RF generators fromflowing through the transmission line and damaging their respective RFgenerator. In this configuration, the separate RF filter assembly caninclude a low-pass filter, a notch filter or a high-pass filter that isable to allow the generated RF waveform to pass and block the RFwaveform(s) generated by the other RF generator(s).

In some embodiments, it may also be desirable to utilize two or moresets of PV generators that are each configured to separately provide aPV waveform to the biasing electrode 104 and/or edge control electrode115. In this example, each of the PV waveform generators 150 (only oneis shown in FIG. 3A or 3B) will include a PV filter assembly (e.g.,includes a blocking capacitor having a capacitance C_(BC)), which isadapted to prevent a current generated by the output of the other PVgenerator(s) from flowing through the respective PV transmission lines157 and damaging each of the respective PV generators. In addition, eachof the PV waveform generators 150 will also include an RF filterassembly, such as the second filter assembly 151 that is connected inseries with each respective PV waveform generators and is configured toblock the RF frequencies delivered from the other PV waveformgenerators.

In some embodiments, as shown in FIGS. 1A-3B, each of the PV waveformgenerators 150 are configured to provide a pulsed voltage waveformsignal to the biasing electrode 104, and eventually the complex load130, by delivering the generated pulsed voltage waveforms through theblocking capacitor 153 of the chucking module 116 and second filterassembly 151, high-voltage line inductance L_(HV), and effectivecapacitance C_(E). In this case, the system optionally includes achucking module 116 used for chucking, such as “electrically clamping”,the substrate to the substrate receiving surface of the ESC substratesupport. Chucking the substrate allows filling a gap between thesubstrate receiving surface and the non-device side surface of thesubstrate with helium gas (He), which is done in order to provide goodthermal contact between the two and allow substrate temperature controlby regulating the temperature of the ESC substrate support. Combining aDC chucking voltage produced by the chucking module 116 with the pulsedvoltage produced by the PV waveform generator 150 at a biasing electrode104 will result in an additional voltage offset of the pulsed voltagewaveform equal to the DC chucking voltage produced by the chuckingmodule 116. The additional voltage offset can be added or subtractedfrom the offset ΔV illustrated in FIGS. 4A and 5A-5B. The effect of thechucking module 116 on the operation of the PV pulse generator 314 ofthe PV waveform generator 150 can be made negligible by selectingappropriately large blocking capacitor 153 and blocking resistor 154.The blocking resistor 154 schematically illustrates a resistorpositioned within the components connecting the chucking module 116 to apoint within the transmission line 131. The main function of theblocking capacitor 153 of in the simplified electrical circuit is toprotect the PV pulse generator 314 from the DC voltage produced by theDC power supply 155, which thus drops across blocking capacitor 153 anddoes not perturb the PV waveform generator's output. The value ofblocking capacitor 153 is selected such that while blocking only the DCvoltage, it does not present any load to the pulsed bias generator'spulsed voltage output. By selecting a sufficiently large blockingcapacitor 153 capacitance (e.g., 10-80 nF) the blocking capacitor 153 isnearly transparent for a 400 kHz PV waveform signal, which is generatedby the PV waveform generator 150 for example, in that it is much biggerthan any other relevant capacitance in the system and the voltage dropacross this element is very small compared to that across other relevantcapacitors, such as chuck capacitance C_(E), and sheath capacitanceC_(SH). Additionally, in some embodiments, the blocking capacitor 153has a capacitance that is significantly greater than a capacitance ofthe blocking capacitor C_(BC) found in the first filter assembly 162. Insome embodiments, the blocking capacitor 153 has a capacitance that isat least one order of magnitude, or at least two orders of magnitude, orabout three orders of magnitude greater than a blocking capacitor C_(BC)found in the first filter assembly 162. In one example, the capacitanceof blocking capacitor C_(BC) is about 38 pF and the capacitance of theblocking capacitor 153 is about nF.

Referring to FIGS. 3A-3B, the purpose of the blocking resistor 154 inthe chucking module 116 is to block the high-frequency pulsed biasgenerator's voltage and minimize the current it induces in the DCvoltage supply 155. This blocking resistor 154 is sized to be largeenough to efficiently minimize the current through it. For example, aresistance of ≥1 MOhm is used to make a 400 kHz current from the PVwaveform generator 150 into the chucking module 116 negligible. In oneexample, the blocking resistor has a resistance of more than about 500kOhm. The resultant average induced current of the order of 0.5-1 mA isindeed much smaller than a typical limitation for chucking module powersupplies, which is about 5 mA DC current. The components of the biascompensation circuit elements 116A, which include a capacitance 155B, adiode 155C, a resistor 155A, and the blocking resistor 154, togetherform a current suppressing/filtering circuit for the pulsed voltage, sothat pulsed voltage does not induce current through the chucking module116. The blocking resistor 154 is disposed between the DC power supply155 and the output 350 and/or the generator output coupling assembly 181(FIG. 1C). In some embodiments, the diode 155C is connected in parallelwith the blocking resistor 154, wherein the diode 155C is oriented suchthat the anode side of the diode 155C is connected to the PVtransmission line 157.

The second filter assembly 151 includes one or more electrical elementsthat are configured to prevent a current generated by the output of theRF generator 118 from flowing through PV transmission line 157 anddamaging the PV pulse generator 314 of the PV waveform generator 150. Asdiscussed above, the PV transmission line 157 is an assembly thatincludes the coaxial transmission line 106 and transmission line 131. Inone embodiment, the second filter assembly 151 includes a filtercapacitor 151A, which has a capacitance C_(FC), and a filter inductor151B, which has an inductance L_(FL), that are connected in parallel,and are disposed in the transmission line 157 between the PV pulsegenerator 314 and the biasing electrode 104. In some configurations, thesecond filter assembly 151 is disposed between the blocking capacitor153 of the chucking module 116 and the biasing electrode 104. The secondfilter assembly 151 acts as a high impedance (e.g., high Z) to the RFsignal generated from the RF generator 118, and thus inhibits the flowof current to the PV pulse generator 314. In some embodiments, thecapacitance C_(FC) of the filter capacitor 151A is significantly lessthan the capacitance of the blocking capacitor 153, such as at least oneorder of magnitude, or at least two orders of magnitude, or three ordersof magnitude less than the capacitance of the blocking capacitor 153. Inone example, the capacitance C_(FC) of the filter capacitor 151A isabout 51 pF and the capacitance of the blocking capacitor 153 is about40 nF.

As discussed above, the second filter assembly 151 is configured toblock the RF signal, and any associated harmonics from making their wayto the PV pulse generator 314. In some embodiments, the RF signalgenerated by the RF generator is configured to deliver an RF frequencygreater than 400 kHz, such an RF frequency MHz, or MHz, or 3.56 MHz, or≥40 MHz. In some embodiments, to prevent RF power provided from the RFgenerator 118 from damaging the PV pulse generator 314 the second filterassembly 151 includes a filter capacitor 151A that has a capacitance ina range between about 25 pF and 100 pF and a filter inductor 151B thathas an inductance in a range between about 0.1 and 1 μH. In one example,to prevent RF power provided from the RF generator 118 at a frequency of40 MHz from damaging the PV pulse generator 314 the second filterassembly 151 includes a filter capacitor 151A that has a capacitance ofabout 51 pF and a filter inductor 151B that has an inductance of about311 nH. In some embodiments, the blocking capacitor C_(BC) of the firstfilter assembly 162 has a capacitance value that is within one order ofmagnitude of the capacitance value of the filter capacitor 151A of thesecond filter assembly 151.

In some embodiments, as shown in FIGS. 3A-3B, the second filter assembly151 further includes a second filter inductor 151C, which has aninductance L₂, and a second filter capacitor 151E, which has acapacitance C₂, that are coupled between the transmission line 157 andground, and also a third filter inductor 151D, which has an inductanceL₃, and a third filter capacitor 151F, which has a capacitance C₃, thatare also coupled between the transmission line 157 and ground. In someconfigurations, the second filter inductor 151C and third filterinductor 151D may have an inductance between about 0.1 and 1 μH, and thesecond filter capacitor 151E and third filter capacitor 151F have acapacitance between about 25 pF and 100 pF.

Pulse Waveform Examples

As noted above, embodiments of the disclosure provide novel substratebiasing methods that enable the maintaining of a nearly constant sheathvoltage during processing, and thus creating a desired IEDF at thesurface of the substrate, while also providing the ability to separatelycontrol aspects of the plasma formed in the processing volume of theplasma processing chamber by use of one or more RF source assemblies. Insome embodiments, by use of the novel substrate biasing apparatus andmethods disclosed herein, a single-peak (mono-energetic) IEDF can beformed at the surface of the substrate during processing. In otherembodiments, as illustrated in FIG. 4D, a two-peak (bi-energetic) IEDFis formed at the surface of the substrate during processing by use ofone or more of the novel substrate biasing apparatus and methodsdisclosed herein. In some apparatus configuration(s) disclosed herein,such as illustrated in FIG. 1A, also allow for the area of the groundedsurface within the plasma processing chamber to be maximized and thusminimize the power losses to chamber walls and improve the plasmaprocessing efficiency.

As is discussed further below in relation to FIGS. 4A-4C and 5A-5C, thenovel substrate biasing methods, which enable the maintaining of anearly constant sheath voltage during plasma processing, include thedelivery of a series of pulses and/or bursts of pulses during a plasmaprocessing sequence performed on a substrate during a plasma processperformed in the plasma processing chamber. Embodiments of thedisclosure provided herein include the delivery of pulses that have adesired pulsed-voltage waveform (PVWF), which each include multipledifferent phases. As is discussed further below, each PV waveformincludes at least one phase of the multiple phases that are controlledby the delivery of a voltage signal, or in some cases a constant currentsignal, provided from the PV waveform generator 150. Generally, fordiscussion purposes, each pulse of a PV waveform can be segmented intotwo main regions, which include a first region 405 and a second region406, as illustrated in FIGS. 5A-5C. In general, each PV waveform willinclude an amplitude (V_(out)), offset (e.g., ΔV), a pulse period(T_(P)), and a pulse repetition frequency (f_(P)=1/T_(P)).

FIG. 4A illustrates a negative-pulse biasing scheme type of PV waveformthat can be established at the biasing electrode 104 and/or edge controlelectrode 115 by use of a PV waveform generator 150 within a PV sourceassembly. In some embodiments, the PV waveform illustrated in FIG. 4A isseparately established at the biasing electrode 104 and edge controlelectrode 115 by use of the PV waveform generator 150 of a first PVsource assembly 196 and the PV waveform generator 150 of a second PVsource assembly 197, respectively. FIG. 5A illustrates a negative-pulsebiasing scheme type of pulsed voltage waveform in which the PV waveformgenerators 150 is configured to control the generation of a series 550of multiphase negative pulse waveforms 401 to establish the PV waveformat the biasing electrode 104 or edge control electrode 115. In someembodiments, the multiphase negative pulse waveforms 401 includes aseries of repeating cycles, such that a waveform within each cycle has afirst portion that occurs during a first time interval and a secondportion that occurs during a second time interval. The multiphasenegative pulse waveforms 401 will also include a positive voltage-pulsethat is only present during at least a portion of the first timeinterval, and the pulsed voltage waveform is substantially constantduring at least a portion of the second time interval. An output of thePV waveform generator 150 is connected to a negative voltage supply forat least a portion of the second time interval.

The substrate PV waveform 425, as shown in FIG. 4A, is a series of PVwaveforms established at the substrate due to the established PVwaveform formed at the biasing electrode 104 or edge control electrode115 by a PV waveform generator 150. The substrate PV waveform 425 isestablished at the surface of a substrate during processing, andincludes a sheath collapse and ESC recharging phase 450 (or forsimplicity of discussion the sheath collapse phase 450) that extendsbetween point 420 and point 421 of the illustrative substrate PVwaveform 425, a sheath formation phase 451 that extends between point421 and point 422, and an ion current phase 452 that extends betweenpoint 422 and back to the start at point 420 of the next sequentiallyestablished pulse voltage waveform. The plasma potential curve 433, asshown in FIGS. 4A-4C, illustrates the local plasma potential during thedelivery of the negative pulse waveforms 401 that are established at thebiasing electrode 104 and/or edge control electrode 115 by use of one ormore PV waveform generators 150.

In some embodiments, during processing in the processing chamber 100, amultiphase negative pulse waveform 401 is formed when a PV waveformgenerator 150 supplies and controls the delivery of a negative voltageduring two of the phases of the established multiphase negative pulsewaveform 401, such as the portions of the PV waveform that trend in anegative direction and/or are maintained at a negative voltage level(e.g., ion current phase). For example, these negativevoltage-containing portions of the negative pulse waveform 401 would, byanalogy, relate to the sheath formation phase 451 and the ion currentphase 452 illustrated in FIG. 4A for the substrate PV waveform 425. Inthis case, for a multiphase negative pulse waveform 401, the delivery ofa negative voltage from a PV waveform generator 150 occurs during thesecond phase 406, which extends from or between the point 411 (i.e.,peak of multiphase negative pulse waveform 401) and the start of thesheath collapse phase 450 of the substrate PV waveform that coincideswith point 413, as shown in FIG. 4A. In some embodiments, during the ioncurrent phase 452, which coincides with the portion of the establishedmultiphase negative pulse waveform 401 that is between points 412 and413, the PV waveform generator 150 is configured to provide a constantnegative voltage (e.g., V_(OUT)). Due to, for example, the ion current(Ii) depositing positive charge on the substrate surface during the ioncurrent phase 452, the voltage at the substrate surface will increaseover time, as seen by the positive slope of the line between points 422and 420 (FIG. 4A). The voltage increase over time at the substratesurface will reduce the sheath voltage and result in a spread of the ionenergy. Therefore, it is desirable to control and set at least the PVwaveform frequency (1/T_(PD), where T_(PD) is PV waveform period (FIG.5A)) to minimize the effects of the reduction in the sheath voltage andspread of the ion energy.

FIG. 5B illustrates a shaped-pulse biasing scheme type of PV waveform inwhich the PV waveform generator 150 is configured to control thegeneration of a series 551 of multiphase shaped pulse waveforms 441 thatare established at the biasing electrode 104 and/or edge controlelectrode 115. In some embodiments, the multiphase shaped pulse waveform441 is formed by a PV waveform generator 150 that is configured tosupply a positive voltage during one or more phases of a voltage pulse(e.g., first region 405) and a negative voltage during one or morephases of the voltage pulse (e.g., second region 406) by use of one ormore internal switches and DC power supplies.

In some embodiments, as illustrated in FIG. 5C, the PV waveformgenerator 150 is configured to provide a series 552 of multiphasepositive pulse waveforms 431 to the biasing electrode 104 and edgecontrol electrode 115. Each positive pulse in the positive pulsewaveform 431 can include multiple phases, such as a sheath collapsephase, ESC recharging phase, a sheath formation phase and an ion currentphase. In this example, the first region 405 generally includes thesheath collapse phase and ESC recharging phase. The second region 406generally includes the sheath formation phase and the ion current phase.In some embodiments, the multiphase positive pulse waveforms 431includes a series of repeating cycles, such that a waveform within eachcycle has a first portion that occurs during a first time interval and asecond portion that occurs during a second time interval. The multiphasepositive pulse waveforms 431 will also include a positive voltage-pulsethat is only present during at least a portion of the first timeinterval, and the multiphase positive pulse waveforms 431 issubstantially constant during at least a portion of the second timeinterval. An output of the PV waveform generator 150 is connected to apositive voltage supply for at least a portion of a first time interval.

The various pulse voltage waveforms 401, 441 and 431 illustrated inFIGS. 5A, 5B and 5C, respectively, are representative of pulse voltagewaveforms that are provided to the input of the chucking module 116, andthus may differ from the pulse voltage waveforms that is established atthe biasing electrode 104 and edge control electrode 115 as illustratedin FIG. 4A. The DC offset ΔV found in each PV waveform is dependent onvarious properties of the PV waveform generator 150 configuration usedto establish the PV waveform.

FIG. 4B illustrates a processing method in which a series of bursts 462of pulsed voltage waveforms are established at the biasing electrode 104and/or edge control electrode 115 and established at the substratesurface. In the example illustrated in FIG. 4B, a plurality of pulses461 within each burst 462 include a series of negative pulse waveforms401 that are established at the biasing electrode 104 and/or edgecontrol electrode 115. In this example, each of the bursts 462 includepulses 461 that have a PV waveform that has a consistent pulsed voltageshape (e.g., constant voltage magnitude is provided during a portion ofeach PV waveform 401), a burst delivery length T_(ON) that does not varyfrom one burst 462 to another over time and a burst rest length T_(OFF)that does not have a varying length over time. The burst rest lengthT_(OFF) is formed by halting the delivery of the PV waveforms providedduring the burst delivery length T_(ON) time for a period of time. Theduty cycle of the bursts 462, which is the ratio of the length of timethe plurality of pulses are delivered during the burst (i.e., burstdelivery length T_(ON)) divided by the duration of a burst period (i.e.,T_(BD)=T_(ON)+T_(OFF)), is also constant in this example. One willappreciate that in other processing methods, the plurality of pulses 461could include negative pulse waveforms 401, shaped pulse waveforms 441or positive pulse waveforms 431, or combinations thereof. As illustratedin FIG. 4B, during the burst rest length T_(OFF) the biasing electrodepotential curve 436 is primarily controlled by the chucking voltage thatis applied and controlled by the chucking module 116, and thus may be ata different voltage level than the plasma potential.

FIG. 4C illustrates a processing method in which a plurality ofdifferently configured bursts of pulses, such as bursts 462 and bursts463, are established at the biasing electrode 104 and/or edge controlelectrode 115 and established at the substrate surface. FIG. 4Dillustrates an effect created by the performance of the processingmethod illustrated in FIG. 4C on a plot of the IEDF during plasmaprocessing. It is believed that by controlling the delivery of aplurality of differently configured bursts within a repeating cycle itis possible to control the distribution of ion energies such that theIEDF will include two or more discrete IEDF peaks, such as the twodiscrete IEDF peaks illustrated in FIG. 4D are formed by the performanceof the processing method illustrated in FIG. 4C. By way of contrast, inconventional plasma processes that utilize an RF biasing scheme, theIEDF typically has two peaks, which are formed at a low and a highenergy and some ion population that has energies that are in between thetwo peaks, and thus will not desirably form discrete IEDF peaks. Anexample of a conventionally formed IEDF curve is illustrated in FIG. 1Bof U.S. Pat. No. 10,555,412, which is herein incorporated by referencein its entirety. In these conventional biasing schemes, an applied RFvoltage (having a waveform such as the one shown in FIG. 6A) modulatesthe cathode sheath throughout the entire RF period, thus unduly varyingthe sheath voltage drop all of the time and resulting in a dual-peakIEDF. As discussed above, the range of ion energies extending betweenthe two IEDF peaks (i.e., formation non-discrete IEDF peaks) formedduring a conventional process will affect the profile of the etchedfeature walls formed within the surface of the substrate during plasmaprocessing.

In some embodiments of the method illustrated in FIG. 4C, the pluralityof differently configured bursts include a repeating cycle of thedifferently configured bursts that have a repeating cycle length (Main).Each of the bursts 462 and bursts 463 include a plurality of pulses 461that can include negative pulse waveforms 401, shaped pulse waveforms441 or positive pulse waveforms 431, or combinations thereof. In someembodiments, the plurality of differently configured bursts includes atleast two differently configured bursts, such that at least thecharacteristics of the plurality pulses 461 formed during at least twoof the bursts within the plurality of differently configured bursts havedifferent characteristics. In one example, as illustrated in FIG. 4C,the characteristics of the plurality pulses 461 with the bursts 462 havea different pulse voltage magnitude (e.g., different V_(OUT)) than theplurality pulses 461 with the bursts 463, and thus are able to form thetwo IEDF peaks (FIG. 4D) that have different peak heights. In someembodiments, the pulses 461 have a pulse voltage magnitude (V_(OUT)) ofbetween about 1 kilovolt (kV) and about 10 kV. In some embodiments, thecharacteristics of the plurality pulses 461 that are different betweenat least two of the bursts within the repeating cycle include differingindividual PV waveform periods, different pulse voltage magnitudes,different shapes of at least a portion of the PV waveform within thefirst region 405 and a second region 406 (e.g., voltage magnitude, slope(dV/dt)), or other PV waveform characteristics. Each of the bursts 462and 463 have a burst period that includes the burst delivery lengthT_(ON) and burst rest length T_(OFF). Further, the burst period T_(BD)and the burst duty cycle (e.g., T_(ON)/T_(BD)) are based on the burstdelivery length T_(ON) and the burst period T_(BD). In some embodiments,the burst delivery length T_(ON) is between about 50 μs and about 50milliseconds (ms), such as between about 200 μs and about 5 ms, and theburst duty cycle is between about 5%-100%, such as between about 50% andabout 95%. In one example, the burst delivery length T_(ON) is about 800μs, and the burst duty cycle is about 80% for both of the bursts 462 andbursts 463. More specifically, FIG. 4C includes an example of multiplebursts (each containing a plurality of waveform cycles) of an inputpulsed voltage waveform originating from the generator end of agenerator output coupling assembly 181 positioned at the output of thePV waveform generator 150 that is provided to the biasing electrode 104of the substrate support assembly 136. The plurality of differentlyconfigured bursts can be characterized as having differently configuredoffsets (ΔV), burst periods (T_(BD)), burst frequencies(f_(B)=1/T_(BD)), and/or burst duty cycles (Duty=T_(on)/T_(BD)).Therefore, by altering the characteristics of the plurality of pulses461 between two or more of the differently configured bursts, two ormore discrete IEDF peaks can be formed to adjust or alter the plasmaprocessing results achieved on a substrate during processing.

FIG. 5D illustrates a series of PV waveforms formed at a substrateduring processing by establishing a positive pulse waveforms 431 (notshown) or a negative pulse waveforms 401 (not shown) at a biasingelectrode 104 and/or edge control electrode 115 by use of one or more PVwaveform generators 150. The PV waveforms formed at the substrateinclude the substrate PV waveforms 425 formed by the establishment ofthe negative pulse waveforms 401, or substrate PV waveforms 531 formedby the establishment of the positive pulse waveforms 431. In someembodiments, the negative pulse waveforms 401 is formed by establishinga negative voltage at the biasing electrode 104 and/or edge controlelectrode 115 between time T_(N1) and time T_(N2). In some embodiments,the negative voltage provided at the output 350 of the PV waveformgenerator(s) 150, which is provided to the biasing electrode 104 and/oredge control electrode 115, is substantially constant during at least aportion of the second region 406 of the negative pulse waveforms 401. Inone example, the negative voltage provided at the output 350 of the PVwaveform generator(s) 150 is substantially constant for the entiresecond region 406 except for any switching related voltage oscillationsor transitions found at the start and/or end of second region 406.Referring to FIG. 3B, the negative voltage is provided by causing switchS₁ to close and remain closed during the time period between time T_(N1)and time T_(N2), and cause switch S₂ open and remain open during thissame time period. During the other time period that starts at timeT_(N2) and ends at time T_(N1), switch S₁ will open and remain open andswitch S₂ will close and remain closed.

In some embodiments, the positive pulse waveforms 431 is formed byestablishing a positive voltage at the biasing electrode 104 and/or edgecontrol electrode 115 between time T_(P1) and time T_(P2). Referring toFIG. 3A, the positive voltage is provided by causing switch S₁ to closeand remain closed during the time period between time T_(P1) and timeT_(P2), and cause switch S₂ open and remain open during this same timeperiod. During the other time period that starts at time T_(P2) and endsat time T_(P1), switch S₁ will open and remain open and switch S₂ willclose and remain closed. In some embodiments, the positive voltageprovided at the output 350 of the PV waveform generator(s) 150, which isprovided to the biasing electrode 104 and/or edge control electrode 115,is substantially constant during at least a portion of the first region405 of the positive pulse waveforms 431.

As shown in FIG. 5D, the process of establishing the negative pulsewaveforms 401 or positive pulse waveforms 431 at the biasing electrode104 and/edge control electrode 115 will form substrate PV waveforms 425or substrate PV waveforms 531, respectively, that can have differingwaveform characteristics. In one example, it is desirable to formsubstrate PV waveforms 425 that include a longer time period (T_(NNSH))of the waveform cycle where no sheath exists (i.e., formed during ESCrecharging phase 560) when using a negative pulsing process, versusforming substrate PV waveforms 531 that include a shorter time period(T_(PNSH)) of the waveform cycle where no sheath exists (i.e., formedduring ESC recharging phase 570) during a positive pulsing process. Inthis example, the time period T_(NNSH) where no sheath exists during anegative PV waveform can be about 175 nanoseconds (ns) versus the timeperiod T_(PNSH) where no sheath exists during a positive PV waveform canbe about 80 ns.

In either of the processes of establishing pulsed voltage waveforms,such as establishing negative pulse waveforms 401, shaped pulsewaveforms 441 or positive pulse waveforms 431, at the biasing electrode104 and/edge control electrode 115, can enable keeping the sheathvoltage nearly constant for a large percentage (e.g., 85%-90%) of thesubstrate processing time during a plasma process. The waveformsillustrated in FIGS. 4A-5D are only intended to show a simplifiedschematic representations of a pulsed voltage waveform that can be usedwith one of the methods described herein, which can be used duringplasma processing of a substrate. The actual waveforms generated by thePV waveform generators 150 can be significantly more complex and containa number of fine-scale features (e.g., high-frequency oscillationscaused by the presence of inductive elements) that are not shown inFIGS. 3A-3B. However, these fine-scale features are not essential forunderstanding of the underlying physical phenomena determining thegeneral shape of the actual pulsed voltage waveform produced by thepulsed voltage biasing scheme and control methods proposed herein.

Pulsed Voltage Waveform Phases

In general, the pulsed voltage waveforms such as establishing negativepulse waveforms 401, shaped pulse waveforms 441 or positive pulsewaveforms 431, comprises a periodic series of short pulses repeatingwith a period T_(PD), on top of a voltage offset (ΔV). In one example,the period T_(PD) can be between about 1 μs and about 5 μs, such asabout 2.5 μs. A waveform within each period (repetition cycle) includesthe following:

(1) A sheath collapse phase, during which the sheath capacitor C_(sh)(FIGS. 3A-3B) is discharged and the substrate potential is brought tothe level of the local plasma potential (e.g., plasma potential curve433 in FIG. 4A). The sheath collapse phase enables rapid recharging ofthe chuck capacitor C_(E) by electrons provided from the plasma duringthe ESC recharging phase (2).

(2) Recharging of the chuck capacitor C_(E), during the ESC rechargingphase, by rapidly injecting or accumulating an amount of charge ofopposite polarity to the total charge accumulated on the substratesurface during the latter performed ion current phase. The plasmacurrent during this phase is also carried by electrons, namely, in theabsence of the cathode sheath, the electrons reach the substrate andbuild up the surface charge, thus charging the capacitor C_(E).

(3) A negative voltage jump to discharge the processing chamber's straycapacitor, re-form the sheath and set the value of the sheath voltage(V_(SH)) during the sheath formation phase. The beginning of sheathformation (charging of C_(sh)) can be clearly identified as the point,at which the substrate potential starts decreasing below the localplasma potential.

(4) A generally long (e.g., >50%, such as about 80-90% of the PVwaveform cycle duration T) ion current phase, during which the ioncurrent causes accumulation of positive charge on the substrate surfaceand gradually discharges the sheath and chuck capacitors, slowlydecreasing the sheath voltage drop and bringing the substrate potentialcloser to zero. This results in the voltage droop in the substratevoltage waveforms 425 (FIG. 4A) and 531 (FIG. 5D). The generated sheathvoltage droop is a reason why the pulse waveform(s) needs to move to thenext cycle described in (1)-(3) above.

As discussed above, in some embodiments, the processing chamber 100 willat least include one or more RF generators 118, and their associatedfirst filter assembly 162, and one or more PV generators 314, and theirassociated second filter assembly 151, that are together configureddeliver desired waveforms to one or more electrodes disposed within thesubstrate support assembly 136. The software instruction stored inmemory of the controller 126 are configured to cause the generation ofan RF waveform that is configured to establish, maintain and control oneor more aspects of a plasma formed within the processing chamber. Theone or more aspects of the plasma that are controlled can include, butare not limited to, plasma density, plasma chemistry, and ion energy inthe plasma formed in the processing volume 129.

FIG. 6A illustrates a typical sinusoidal RF waveform 601 that hasfrequency (i.e., 1/T_(RF)) that is provided from the RF generator 118.Typically, the one or more aspects of the plasma can be controlled byselecting a desired RF frequency and amount of RF power, and, in somecases, the duty cycle of a pulsed RF signal (i.e., the percentage oftime that the sinusoidal RF signal is “on” (T_(RFON)) versus thepercentage of time the sinusoidal RF signal is “off” (T_(RFOFF))). Theselection of a desired RF frequency is generally performed by selectingan RF generator (e.g., 2 MHz, 13.56 MHz, or 40 MHz RF generator) that isconfigured to provide a varying amount of RF power at one or morefrequencies within a selected narrow RF frequency range.

FIG. 6B illustrates a pulsed RF waveform 602 that can provided from theRF generator 118 during a plasma process. The formed the pulsed RFwaveform 602 can have a RF pulse period T_(RFP) within the RF pulsed RFsequence, and “on” and “off” times (i.e., T_(RFON) and T_(RFOFF)respectively) within which the sinusoidal RF waveform 601 is provided ornot provided by the RF generator 118.

FIG. 6C illustrates a method in which a pulsed RF waveform 602 providedfrom the RF generator 118 is synchronized with a series of bursts 612,622 or 632 provided to the biasing electrode 104 and/or edge controlelectrode 115 by use of one or more PV waveform generators 150 and thecontroller 126. While the bursts 615, 625, 635 within each series ofbursts 612, 622, 632, as shown in FIG. 6C, includes a single consistenttype of burst (i.e., pulses 461 have the same pulse characteristics), itis contemplated that the bursts within each series of bursts generatedby the one or more PV waveform generators 150 could include differentlyconfigured bursts, such as bursts 462, 463 of FIG. 4C. Similarly, insome embodiments, the RF pulses within the RF waveform 602 may include aseries of differently configured RF pulses. The bursts 615, 625 or 635each include a plurality of pulses 461 that can include negative pulsewaveforms 401, shaped pulse waveforms 441 or positive pulse waveforms431, or combinations thereof that can be established at either or boththe biasing electrode 104 and edge control electrode 115.

In one example, during processing a series of bursts 612 that include aplurality of bursts 615 are provided to the biasing electrode 104 and/oredge control electrode 115 and are synchronized with delivery of thepulsed RF waveform 602. In this example, each of the plurality of bursts615 have the same burst delivery length, burst rest length, and burstperiod as the RF pulse delivery length T_(RFON), RF pulse rest lengthT_(RFOFF) and RF pulse period T_(RFP) of the RF pulses within the pulsedRF waveform 602.

In another example, during processing a series of bursts 622, whichinclude a plurality of bursts 625 are provided to the biasing electrode104 and/or edge control electrode 115 and are synchronized with thedelivery of pulsed RF waveform 602. In this example, each of theplurality of bursts 625 have the same burst delivery length, burst restlength, and burst period as the RF pulse delivery length T_(RFON), RFpulse rest length T_(RFOFF) and RF pulse period T_(RFP) of the RF pulseswithin the pulsed RF waveform 602. However, in this example, a delayperiod T_(DE) is provided such that the start of each burst 625 occursat a time after at least a portion of each of the RF pulse within thepulsed RF waveform 602 are delivered, which is also referred to hereinas a positive delay period. It may also or alternately be desirable todelay the delivery of the RF pulse relative to the delivery of thebursts 625 such that the delivery of the RF pulses occurs after at leasta portion of the bursts 625 are delivered (i.e., negative delay period).

In another example, during processing a series of bursts 632, whichinclude a plurality of bursts 635 are provided to the biasing electrode104 and/or edge control electrode 115 and synchronized with the deliveryof pulsed RF waveform 602. In this example, each of the plurality ofbursts 635 have the same burst period as the RF pulses within the pulsedRF waveform 602. However, in this example the burst delivery length andburst rest length are different from the RF pulses within the pulsed RFwaveform 602. As illustrated in FIG. 6C, the burst delivery length ofeach burst 635 is longer than the RF pulse delivery length T_(RFON) byperiod of time TDS. In this case, the duty cycles between the deliveryof the bursts 635 and pulsed RF waveform 602 are different.

While the series of bursts 612, 622, 632 illustrated in FIG. 6C eachinclude constant burst delivery length and duty cycle it is contemplatedthat the burst delivery length and/or duty cycle in a series of burstscould vary over time. Also, while the series of bursts 622 illustratedin FIG. 6C each include constant a delay period T_(DE) it iscontemplated that the delay period in a series of bursts could vary overtime. Also, while the series of bursts 632 illustrated in FIG. 6C eachinclude constant a burst delivery length and constant delay period it iscontemplated that the burst delivery length in a series of bursts couldvary over time and/or it may be desirable to delay the delivery of theRF pulses relative to the delivery of the bursts 625.

In another example, as illustrated in FIG. 6D, during processing aseries of bursts 642, which include a plurality of bursts 645 areprovided to the biasing electrode 104 and/or edge control electrode 115and are synchronized with the delivery of pulsed RF waveform 602. Inthis example, each of the plurality of bursts 645 have a different burstdelivery length, burst rest length, and burst period from the RF pulsedelivery length T_(RFON), and RF pulse rest length T_(RFOFF) of the RFpulses within the pulsed RF waveform 602. In this example, a start delayperiod T_(DE) is provided such that the start of each burst 645 occursat a time after at least a portion of each of the RF pulse within thepulsed RF waveform 602 are delivered, and also an end delay period TEDis provided such that the end of each burst 645 occurs before the RFpulse period T_(RFP) ends. In this example, the duty cycle of each burst645 is less than the RF pulse.

In another example, as illustrated in FIG. 6E, during processing aseries of bursts 652, which include a plurality of bursts 655 and 656are provided to the biasing electrode 104 and/or edge control electrode115 and are synchronized with the delivery of a multi-level pulsed RFwaveform 603. The multi-level pulsed RF waveform 603 includes aplurality of RF pulse power levels 604 and 605 that are formed by thedelivery of sinusoidal RF waveform 601 at different power levels by useof an RF generator. In this example, each of the plurality of bursts 655and 656 are synchronized with the changes in the RF pulse power levels604 and 605. Each of the plurality of bursts 655 and 656 include aplurality of negative pulse waveforms 401 that are supplied at differentvoltage levels as illustrated by the difference in the negative levelsof each of the applied voltage level peaks for the each of the bursts655 and 656. In some embodiments, as illustrated in FIG. 6E, thetransitions between the bursts 655 and 656 and/or RF pulse power levels604 and 605 are not separated by a burst rest length T_(OFF) time or aRF pulse rest length T_(RFOFF) time, respectively.

FIG. 6F, which includes the series of bursts 652 and multi-level pulsedRF waveform 603 illustrated in FIG. 6E, schematically illustrates a TTLsignal waveform that is used synchronize the delivery of the series ofbursts 652 and multi-level pulsed RF waveform 603. In some embodiments,the TTL signal waveform is provided to each PV waveform generator 150and RF generator 118 by the controller 126 so that the delivery of theseries of bursts 652 and multi-level pulsed RF waveform 603 can besynchronized. In other embodiments, the TTL signal waveform is providedto each PV waveform generator 150 from a master RF generator 118 so thatthe delivery of the series of bursts 652 and multi-level pulsed RFwaveform 603 provided from the master RF generator 118 can besynchronized. The TTL signal waveform can include multi-level pulsesthat include one or more signal characteristics that are used by theeach PV waveform generator 150 and/or RF generator 118 to determine adesired PV waveform characteristic or RF signal waveform characteristicthat is to be provided from the PV waveform generator 150 and/or RFgenerator 118. In one example, the magnitude of the signal waveform(e.g., voltage level(s)) at various different times during a processingsequence is used by the each PV waveform generator 150 to determine thedesired PV waveform output voltage level and is used by the RF generator118 to determine a desired RF power level to be provided.

In another example, as illustrated in FIG. 6G, during processing aseries of bursts 662, which include a plurality of bursts 665 and 667,are provided to the biasing electrode 104 and/or edge control electrode115 and are synchronized with the delivery of a multi-level pulsed RFwaveform 606. The multi-level pulsed RF waveform 606 includes aplurality of RF pulse power levels 607 and 608 that are formed by thedelivery of the sinusoidal RF waveform 601 at different power levels byuse of an RF generator. The multi-level pulsed RF waveform 606 mayinclude RF pulse rest length T_(RFOFF) times, which is illustrated bythe RF rest time 609, that is disposed between the transition from thefirst power level 607 to the second power level 608. In someembodiments, an RF pulse rest length T_(RFOFF) time is disposed at eachtransition between RF pulse power levels 607 and 608. The transitionsbetween in each of the plurality of bursts 665 and 667 are synchronizedwith the changes in the RF pulse power levels 607 and 608. Each of theplurality of bursts 665 and 667 include a plurality of negative pulsewaveforms 401 that are supplied at different voltage levels asillustrated by the difference in the negative levels of each of thepeaks of the each of the bursts 665 and 667. In some embodiments, thetransition from burst 667 to burst 665 is separated by a burst restlength T_(OFF) time, while the transition from burst 665 to burst 667 isnot separated by a burst rest length T_(OFF) time. However, in someembodiments, the transition from burst 665 to burst 667 is separated bya burst rest length T_(OFF) time, while the transition from burst 667 toburst 665 is not separated by a burst rest length T_(OFF) time. Thetransitions from burst 665 to burst 667 and from burst 667 to burst 665may each be separated by a burst rest length T_(OFF) time.

FIG. 6G, also illustrates a TTL signal waveform that can be used to helpsynchronize the delivery of the series of bursts 662 and multi-levelpulsed RF waveform 606. As similarly discussed above, the TTL signalwaveform is provided to the each PV waveform generator 150 and RFgenerator 118 by the controller 126, or the TTL signal waveform isprovided to the each PV waveform generator 150 from a master RFgenerator 118 so that the delivery of the series of bursts 662 andmulti-level pulsed RF waveform 606 can be synchronized. As shown in FIG.6G, the magnitude of the signal waveform at various different timesduring a processing sequence is used by the each PV waveform generator150 to determine the desired PV waveform output voltage level and isused by the RF generator 118 to determine a desired RF power level. Insome configurations, information provided in one or more of the levelsof the TTL signal waveform, such as level LS2 in FIG. 6G, is used todetermine a desired duty cycle, number of pulse in a burst and/or pulsemagnitude for one or more of the bursts 665 and 667, such as burst 667,and/or duty cycle and/or RF pulse magnitude for the RF waveform 606 isdetermined from characteristics of the TTL signal waveform.

FIG. 6H illustrates an alternate version of the pulse sequenceillustrated FIG. 6G. The pulse configuration shown in FIG. 6H isreferred to herein as a Low-High (LH) PV pulse sequence as compared tothe High-Low (HL) PV pulse sequence shown in FIG. 6G. As illustrated inFIG. 6H, the bursts 665 and 667 of the series of bursts 662 and the RFpulse power levels 607 and 608 of the multi-level pulsed RF waveform 606are sequentially positioned differently in time. In this configuration,the bursts 665 and 667 and RF pulse power levels 607 and 608 have beenreordered in time such that burst 667 precedes the delivery of burst665, and RF pulse power level 607 precedes the delivery of RF pulsepower level 608.

In some embodiment, a series of bursts, such as the series of bursts612, 622 or 632, are synchronized and separately provided to the biasingelectrode 104 and the edge control electrode 115 by use of one or morePV waveform generators 150 and the controller 126. In addition, asdiscussed above, a pulsed RF waveform 602 can be synchronized with aseries of bursts 612, 622 or 632 that can be provided to the biasingelectrode 104 and the edge control electrode 115 by use of one or morePV waveform generators 150 and the controller 126. In one example, aseries of bursts 612 are provided to the biasing electrode 104 from thePV waveform generator 150 of the first PV source assembly 196 and aseries of bursts 612 are provided to the edge control electrode 115 fromthe PV waveform generator 150 of the second PV source assembly 197,which are synchronized with the delivery of the pulsed RF waveform 602.

In some embodiments, the bursts and/or series of bursts provided to thebiasing electrode 104 and the bursts and/or series of bursts provided tothe edge control electrode have one or more different characteristics.In one example, the pulsed voltage waveforms provided in a burstprovided to the biasing electrode 104 is different from the pulsedvoltage waveforms provided in a burst that is simultaneously provided tothe edge control electrode 115. In another example, the bursts providedin a series of burst provided to the biasing electrode 104 (e.g., burst615) have a different burst delivery length from the bursts (e.g., burst635) provided in a series of burst that are provided to the edge controlelectrode 115. In another example, the bursts provided in a series ofburst provided to the biasing electrode 104 are staggered in time fromthe bursts provided in a series of burst that are provided to the edgecontrol electrode 115. In this example, the bursts 615 of the series ofbursts 612 are provided to the biasing electrode 104 and the bursts 625of the series of bursts 622 are provided to the edge control electrode115, and thus the timing of the delivery of bursts provided to thebiasing electrode 104, edge control electrode and pulsed RF waveform 602can be separately adjusted relative to one another.

In some embodiments, the PV waveforms provided to the biasing electrode104 and the edge control electrode 115 are synchronized and identical inshape except for the amplitudes of the individual pulses provided toeach electrode may be different. The differing PV waveform amplitudeapplied to the biasing electrode 104 and the edge control electrode 115can be used control the “edge tilt” of the etched features formed on asubstrate. In one example, the PV waveforms within a first burst that isprovided to the biasing electrode 104 and the edge control electrode 115are synchronized and identical in shape, and the peak-to-peak voltage ofthe PV waveform applied to the edge control electrode 115 is greaterthan the peak-to-peak voltage of the PV waveform applied to the biasingelectrode 104. In another example, the PV waveforms within a secondburst that is provided to the biasing electrode 104 and the edge controlelectrode 115 are synchronized and identical in shape, and thepeak-to-peak voltage of the PV waveform applied to the edge controlelectrode 115 is less than the peak-to-peak voltage of the PV waveformapplied to the biasing electrode 104.

In some embodiments, the software instructions stored in memory of thecontroller 126 are configured to cause the generation of apulsed-voltage (PV) waveform and/or bursts of pulsed-voltage (PV)waveforms that are used to establish a nearly constant sheath voltageand thus create a desired IEDF at the surface of the substrate duringplasma processing in the processing chamber. The control ofpulsed-voltage (PV) waveform and/or bursts of pulsed-voltage (PV)waveforms enables the precise control over the shape of IEDF and numberof peaks with IEDF, and thus better control the profile of the featuresformed in the surface of the substrate. The control of thepulsed-voltage (PV) waveform and/or bursts of pulsed-voltage (PV)waveforms will typically include the delivery of a desired voltagesignal during one or more of the phases of the pulsed-voltage (PV)waveforms, and then allow the shape of the remaining phases of thepulsed-voltage (PV) waveform to evolve naturally during the rest of thewaveform period T_(PD). The software stored in memory of the controller126 will also include instructions that are used to control the varioushardware and electrical components within the processing chamber 100,and processing system in which the processing chamber is disposed, toperform the various process tasks and various process sequences neededto synchronized the delivery of RF waveform(s), pulsed-voltage (PV)waveforms and/or bursts of pulsed-voltage (PV) waveforms to one or moreelectrodes within a processing chamber 100.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A plasma processing chamber, comprising: asubstrate support assembly comprising a first electrode that is disposeda first distance from a substrate supporting surface of the substratesupport assembly; a first pulsed-voltage waveform generator electricallycoupled to the first electrode; a second pulsed-voltage waveformgenerator electrically coupled to a second electrode disposed in thesubstrate support assembly radially outward of the first electrode; anda controller comprising a memory that includes computer programinstructions stored therein, and the computer program instructions whenexecuted by a processor of the controller cause: a delivery, by use ofthe second pulsed-voltage waveform generator, of a series of voltagewaveform pulses to the second electrode, wherein the series of voltagewaveform pulses comprise a first voltage waveform pulses and a secondvoltage waveform pulses, the first voltage waveform pulses comprises afirst direct current power level and a first voltage waveform pulsesduration, and the second voltage waveform pulses comprises a seconddirect current power level and a second voltage waveform pulsesduration, and a delivery, by use of the first pulsed-voltage waveformgenerator, of a series of pulsed voltage waveform bursts that comprise afirst voltage waveform that is established at the first electrode,wherein the series of pulsed voltage waveform bursts comprise a firstpulsed voltage waveform burst and a second pulsed voltage waveform burstthat comprise a first burst duration and a second burst duration,respectively, the first pulsed voltage waveform burst comprises a firstportion of the first voltage waveform that comprises a series of voltagepulses that comprise a first voltage pulse phase and a second voltagepulse phase, and the second pulsed voltage waveform burst comprises asecond portion of the first voltage waveform that comprises a series ofvoltage pulses that comprise a first voltage pulse phase and a secondvoltage pulse phase, and during the second voltage pulse phase of theseries of voltage pulses of the first and the second portion of thefirst voltage waveforms the first pulsed-voltage waveform generatorestablishes a negative voltage at the first electrode.
 2. The plasmaprocessing chamber of claim 1, wherein the computer program instructionswhen executed by the processor of the controller further causes: each ofthe pulsed voltage waveform bursts within the series of pulsed voltagewaveform bursts have the same burst period as each of the voltagewaveform pulses within the series of voltage waveform pulses.
 3. Theplasma processing chamber of claim 1, wherein pulsed voltage waveformbursts include a plurality of pulses that can include negative pulsewaveforms, shaped pulse waveforms or positive pulse waveforms, orcombinations thereof.
 4. The plasma processing chamber of claim 1,wherein the PV generator is a sourcing and not a sinking supply.
 5. Theplasma processing chamber of claim 4, wherein the PV generator onlypasses a current in one direction and the output can charge but notdischarge a capacitor.
 6. The plasma processing chamber of claim 4,wherein when a switch remains in the open position, the voltage acrossthe output of the PV waveform generator is not controlled by the PVgenerator and is instead determined by the interaction of its internalcomponents with other circuit elements.
 7. The plasma processing chamberof claim 1, the circuit elements include the following elements: aresistor; a resistor and an inductor connected in series; and a switchwhich permits a positive current flow towards the ground.
 8. The plasmaprocessing chamber of claim 1, wherein the controller is furtherconfigured to provide a plurality of differently configured burstsincluding a repeating cycle of the differently configured bursts thathave a repeating cycle length.
 9. The plasma processing chamber of claim1, further comprising: a generator output coupling assembly that isconfigured to form an electrical connection between the firstpulsed-voltage waveform generator and the first electrode; and achucking assembly comprising: a chucking power supply that iselectrically coupled to the generator output coupling assembly; and ablocking resistor that has a resistance of more than about 500 kOhm thatis disposed between the chucking power supply and the generator outputcoupling assembly.
 10. A method of processing a substrate in a plasmaprocessing chamber, comprising: delivering, by use of a firstpulsed-voltage waveform generator, a series of pulsed voltage waveformbursts that comprise a first voltage waveform that is established at afirst electrode, wherein the series of pulsed voltage waveform burstscomprise a first pulsed voltage waveform burst and a second pulsedvoltage waveform burst that comprise a first burst duration and a secondburst duration, respectively, the first pulsed voltage waveform burstcomprises a first portion of the first voltage waveform that comprises aseries of voltage pulses that comprise a first voltage pulse phase and asecond voltage pulse phase, and the second pulsed voltage waveform burstcomprises a second portion of the first voltage waveform that comprisesa series of voltage pulses that comprise a first voltage pulse phase anda second voltage pulse phase, and during the second voltage pulse phaseof the series of voltage pulses of the first and the second portion ofthe first voltage waveform the first pulsed-voltage waveform generatorestablishes a negative voltage at the first electrode; and delivering,by use of a second pulsed-voltage waveform generator, a series of secondpulsed voltage waveform bursts that comprise a second voltage waveformthat is established at a second electrode, wherein the second electrodecircumscribes the first electrode.
 11. The method of claim 10, whereineach of the pulsed voltage waveform bursts include negative pulsewaveforms, shaped pulse waveforms or positive pulse waveforms, orcombinations thereof.
 12. The method of claim 10, wherein acharacteristics of the first pulsed voltage waveform burst and thesecond pulsed voltage waveform burst have a different pulse voltagemagnitude and are able to form the two different Ion Energy DistributionFunction peaks that have different peak heights.
 13. The method of claim12, wherein the characteristics of the plurality pulses that aredifferent between of the first pulsed voltage waveform burst and thesecond pulsed voltage waveform within the repeating cycle includediffering individual PV waveform periods, different pulse voltagemagnitudes, different shapes of at least a portion of the PV waveformwithin the first region and a second region.
 14. The method of claim 10,the pulses have a pulse voltage magnitude (VOUT) of between about 1kilovolt (kV) and about 10 kV.
 15. The method of claim 14, whereinsynchronizing the delivery of the first voltage waveform to the firstelectrode with the delivery of the second voltage waveform to the secondelectrode comprises providing a signal waveform to the firstpulsed-voltage waveform generator and the second pulsed-voltage waveformgenerator.
 16. The method of claim 12, wherein the first pulsed voltagewaveform burst and the second pulsed voltage waveform burst have a burstperiod that includes the burst delivery length T_(ON) and burst restlength T_(OFF), and the burst period and the burst duty cycle are basedon the burst delivery length T_(ON) and the burst period T_(BD).
 17. Themethod of claim 16, wherein the burst delivery length is between about50 μs and about 50 milliseconds (ms), and the burst duty cycle isbetween about 50% and about 95%.
 18. The method of claim 17, wherein theplurality of differently configured bursts can be characterized ashaving differently configured offsets, burst periods, burst frequenciesand burst duty cycles.
 19. The method of claim 10, further comprising:providing to the biasing electrode a series of first DC pulse bursts,and synchronizing the bursts at the biasing electrode with a pluralityof second DC pulse bursts at the edge control electrode.
 20. The methodof claim 19, wherein the series of first DC pulse bursts and theplurality of second DC pulse bursts include a plurality of negativepulse waveforms that are supplied at different voltage levels, whereinthe series of first DC pulse bursts and the plurality of second DC pulsebursts each have a difference in the negative levels of the appliedvoltage level peaks.